Renamed LinearProgramming to Simplex
[org.ibex.core.git] / src / org / ibex / util / Simplex.java
diff --git a/src/org/ibex/util/Simplex.java b/src/org/ibex/util/Simplex.java
new file mode 100644 (file)
index 0000000..e8871ca
--- /dev/null
@@ -0,0 +1,1341 @@
+package org.ibex.util;
+import java.io.* ;
+import java.util.* ;
+
+public class Simplex {
+
+    public final static short FAIL = -1;
+    
+    public final static short NULL = 0;
+    public final static short FALSE = 0;
+    public final static short TRUE = 1;
+    
+    public final static short DEFNUMINV = 50;
+    
+    /* solve status values */
+    public final static short OPTIMAL = 0;
+    public final static short MILP_FAIL = 1;
+    public final static short INFEASIBLE = 2;
+    public final static short UNBOUNDED = 3;
+    public final static short FAILURE = 4;
+    public final static short RUNNING = 5;
+    
+    /* lag_solve extra status values */
+    public final static short FEAS_FOUND = 6;
+    public final static short NO_FEAS_FOUND = 7;
+    public final static short BREAK_BB = 8;
+    
+    public final static short FIRST_NI =       0;
+    public final static short RAND_NI = 1;
+    
+    public final static short LE = 0;
+    public final static short EQ = 1;
+    public final static short GE = 2;
+    public final static short OF = 3;
+    
+    public final static short MAX_WARN_COUNT = 20;
+    
+    public final static float DEF_INFINITE = (float)1e24; /* limit for dynamic range */
+    public final static float DEF_EPSB = (float)5.01e-7; /* for rounding RHS values to 0 determine     
+                                               infeasibility basis */
+    public final static float DEF_EPSEL = (float)1e-8; /* for rounding other values (vectors) to 0 */
+    public final static float DEF_EPSD  = (float)1e-6; /* for rounding reduced costs to zero */
+    public final static float DEF_EPSILON = (float)1e-3; /* to determine if a float value is integer */
+    
+    public final static float PREJ = (float)1e-3;  /* pivot reject (try others first) */
+    
+    public final static int ETA_START_SIZE = 10000; /* start size of array Eta. Realloced if needed */
+
+    static class Ref {
+        float value;
+        public Ref(float v) { value = v; }
+    }
+
+    //public static class Simplex {
+        /* Globals used by solver */
+        short JustInverted;
+        short Status;
+        short Doiter;
+        short DoInvert;
+        short Break_bb;
+
+        public short active;           /*TRUE if the globals point to this structure*/
+        public short debug;           /* ## Print B&B information */
+        public short trace;           /* ## Print information on pivot selection */
+        public int         rows;               /* Nr of constraint rows in the problem */
+        int       rows_alloc;          /* The allocated memory for Rows sized data */
+        int       columns_alloc;  
+        int       sum;                /* The size of the variables + the slacks */
+        int       sum_alloc;
+        int       non_zeros;          /* The number of elements in the sparce matrix*/
+        int       mat_alloc;           /* The allocated size for matrix sized 
+                                           structures */
+        MatrixArray  mat;                /* mat_alloc :The sparse matrix */
+        MatrixArray  alternate_mat;                /* mat_alloc :The sparse matrix */
+        int[]     col_end;            /* columns_alloc+1 :Cend[i] is the index of the
+                                         first element after column i.
+                                         column[i] is stored in elements 
+                                         col_end[i-1] to col_end[i]-1 */
+        int[]     col_no;             /* mat_alloc :From Row 1 on, col_no contains the
+                                         column nr. of the
+                                         nonzero elements, row by row */
+        short     row_end_valid;       /* true if row_end & col_no are valid */
+        int[]     row_end;            /* rows_alloc+1 :row_end[i] is the index of the 
+                                         first element in Colno after row i */
+        float[]  orig_rh;            /* rows_alloc+1 :The RHS after scaling & sign 
+                                         changing, but before `Bound transformation' */
+        float[]  rh;                   /* rows_alloc+1 :As orig_rh, but after Bound 
+                                           transformation */
+        float[]  rhs;          /* rows_alloc+1 :The RHS of the curent simplex  
+                                  tableau */
+        float[]  orig_upbo;          /* sum_alloc+1 :Bound before transformations */
+        float[]  orig_lowbo;           /*  "       "                   */
+        float[]  upbo;               /*  "       "  :Upper bound after transformation 
+                                          & B&B work*/
+        float[]  lowbo;              /*  "       "  :Lower bound after transformation
+                                          & B&B work */
+
+        short     basis_valid;        /* TRUE is the basis is still valid */
+        int[]     bas;                /* rows_alloc+1 :The basis column list */
+        short[]   basis;              /* sum_alloc+1 : basis[i] is TRUE if the column
+                                         is in the basis */
+        short[]   lower;              /*  "       "  :TRUE is the variable is at its 
+                                          lower bound (or in the basis), it is FALSE
+                                          if the variable is at its upper bound */
+
+        short     eta_valid;          /* TRUE if current Eta structures are valid */
+        int       eta_alloc;          /* The allocated memory for Eta */
+        int       eta_size;           /* The number of Eta columns */
+        int       num_inv;            /* The number of float pivots */
+        int       max_num_inv;        /* ## The number of float pivots between 
+                                         reinvertions */
+        float[]  eta_value;          /* eta_alloc :The Structure containing the
+                                         values of Eta */
+        int[]     eta_row_nr;         /*  "     "  :The Structure containing the Row
+                                          indexes of Eta */
+        int[]     eta_col_end;        /* rows_alloc + MaxNumInv : eta_col_end[i] is
+                                         the start index of the next Eta column */
+
+        short      bb_rule;            /* what rule for selecting B&B variables */
+
+        short     break_at_int;       /* TRUE if stop at first integer better than
+                                         break_value */
+        float    break_value;        
+
+        float    obj_bound;          /* ## Objective function bound for speedup of 
+                                         B&B */
+        int       iter;               /* The number of iterations in the simplex
+                                         solver () */
+        int       total_iter;         /* The total number of iterations (B&B) (ILP)*/ 
+        int       max_level;          /* The Deepest B&B level of the last solution */
+        int        total_nodes;        /* total number of nodes processed in b&b */
+        public float[]  solution;           /* sum_alloc+1 :The Solution of the last LP, 
+                                         0 = The Optimal Value, 
+                                         1..rows The Slacks, 
+                                         rows+1..sum The Variables */
+        public float[]  best_solution;      /*  "       "  :The Best 'Integer' Solution */
+        float[]  duals;              /* rows_alloc+1 :The dual variables of the
+                                         last LP */
+  
+        short     maximise;           /* TRUE if the goal is to maximise the 
+                                         objective function */
+        short     floor_first;        /* TRUE if B&B does floor bound first */
+        short[]   ch_sign;            /* rows_alloc+1 :TRUE if the Row in the matrix
+                                         has changed sign 
+                                         (a`x > b, x>=0) is translated to 
+                                         s + -a`x = -b with x>=0, s>=0) */ 
+
+        int        nr_lagrange;        /* Nr. of Langrangian relaxation constraints */
+        float[][]lag_row;              /* NumLagrange, columns+1:Pointer to pointer of 
+                                           rows */
+        float[]  lag_rhs;              /* NumLagrange :Pointer to pointer of Rhs */
+        float[]  lambda;               /* NumLagrange :Lambda Values */
+        short[]   lag_con_type;       /* NumLagrange :TRUE if constraint type EQ */
+        float    lag_bound;            /* the lagrangian lower bound */
+
+        short     valid;               /* Has this lp pased the 'test' */
+        float    infinite;           /* ## numercal stuff */
+        float    epsilon;            /* ## */
+        float    epsb;               /* ## */
+        float    epsd;               /* ## */
+        float    epsel;              /* ## */
+
+        int     Rows;
+        int     columns;
+        int     Sum;
+        int     Non_zeros;
+        int     Level;
+        MatrixArray  Mat;
+        int[]     Col_no;
+        int[]     Col_end;
+        int[]     Row_end;
+        float[]    Orig_rh;
+        float[]    Rh;
+        float[]    Rhs;
+        float[]    Orig_upbo;
+        float[]    Orig_lowbo;
+        float[]    Upbo;
+        float[]    Lowbo;
+        int[]     Bas;
+        short[]   Basis;
+        short[]   Lower;
+        int     Eta_alloc; 
+        int     Eta_size;           
+        float[]    Eta_value;
+        int[]     Eta_row_nr;
+        int[]     Eta_col_end;
+        int     Num_inv;
+        float[]    Solution;
+        public float[]    Best_solution;
+        float    Infinite;
+        float    Epsilon;
+        float    Epsb;
+        float    Epsd;
+        float    Epsel;
+  
+        float  TREJ;
+        float  TINV;
+  
+        short   Maximise;
+        short   Floor_first;
+        float    Extrad;
+
+        int     Warn_count; /* used in CHECK version of rounding macro */
+
+        public Simplex (int nrows, int ncolumns, int matalloc) {
+            int nsum;  
+            nsum=nrows+ncolumns;
+            rows=nrows;
+            columns=ncolumns;
+            sum=nsum;
+            rows_alloc=rows;
+            columns_alloc=columns;
+            sum_alloc=sum;
+            mat_alloc=matalloc;
+            eta_alloc=10000;
+            max_num_inv=DEFNUMINV;
+            col_no = new int[mat_alloc];
+            col_end = new int[columns + 1];
+            row_end = new int[rows + 1];
+            orig_rh = new float[rows + 1];
+            rh = new float[rows + 1];
+            rhs = new float[rows + 1];
+            orig_upbo = new float[sum + 1];
+            upbo = new float[sum + 1];
+            orig_lowbo = new float[sum + 1];
+            lowbo = new float[sum + 1];
+            bas = new int[rows+1];
+            basis = new short[sum + 1];
+            lower = new short[sum + 1];
+            eta_value = new float[eta_alloc];
+            eta_row_nr = new int[eta_alloc];
+            eta_col_end = new int[rows_alloc + max_num_inv];
+            solution = new float[sum + 1];
+            best_solution = new float[sum + 1];
+            duals = new float[rows + 1];
+            ch_sign = new short[rows + 1];
+            mat = new MatrixArray(mat_alloc);
+            alternate_mat = new MatrixArray(mat_alloc);
+        }
+        
+        public void init(int ncolumns) {
+            int nsum;  
+            int nrows = 0;
+            nsum=nrows+ncolumns;
+            active=FALSE;
+            debug=FALSE;
+            trace=FALSE;
+            rows=nrows;
+            columns=ncolumns;
+            sum=nsum;
+            obj_bound=DEF_INFINITE;
+            infinite=DEF_INFINITE;
+            epsilon=DEF_EPSILON;
+            epsb=DEF_EPSB;
+            epsd=DEF_EPSD;
+            epsel=DEF_EPSEL;
+            non_zeros=0;
+
+            for(int i = 0; i < mat_alloc; i++) { set_row_nr(mat,i, 0); set_value(mat, i, 0); }
+            for(int i = 0; i < mat_alloc; i++)   col_no[i] = 0;
+            for(int i = 0; i < columns + 1; i++) col_end[i] = 0;
+            for(int i = 0; i < rows + 1; i++)    row_end[i] = 0;
+            for(int i = 0; i < rows + 1; i++)   orig_rh[i] = 0;
+            for(int i = 0; i < rows + 1; i++)   rh[i] = 0;
+            for(int i = 0; i < rows + 1; i++)   rhs[i] = 0;
+            for(int i = 0; i <= sum; i++)       orig_upbo[i]=infinite;
+            for(int i = 0; i < sum + 1; i++)    upbo[i] = 0;
+            for(int i = 0; i < sum + 1; i++)    orig_lowbo[i] = 0;
+            for(int i = 0; i < sum + 1; i++)    lowbo[i] = 0;
+            for(int i = 0; i <= rows; i++)      bas[i] = 0;
+            for(int i = 0; i <= sum; i++)       basis[i] = 0;
+            for(int i = 0; i <= rows; i++)     { bas[i]=i; basis[i]=TRUE; }
+            for(int i = rows + 1; i <= sum; i++) basis[i]=FALSE;
+            for(int i = 0 ; i <= sum; i++)       lower[i]=TRUE;
+            for(int i = 0; i < eta_alloc; i++) eta_value[i] = 0;
+            for(int i = 0; i < eta_alloc; i++) eta_row_nr[i] = 0;
+            for(int i = 0; i < rows_alloc + max_num_inv; i++) eta_col_end[i] = 0;
+            for(int i = 0; i <= sum; i++) solution[i] = 0;
+            for(int i = 0; i <= sum; i++) best_solution[i] = 0;
+            for(int i = 0; i <= rows; i++) duals[i] = 0;
+            for(int i = 0; i <= rows; i++) ch_sign[i] = FALSE;
+
+            row_end_valid=FALSE;
+            bb_rule=FIRST_NI;
+            break_at_int=FALSE;
+            break_value=0;
+            iter=0;
+            total_iter=0;
+            basis_valid=TRUE; 
+            eta_valid=TRUE;
+            eta_size=0;
+            nr_lagrange=0;
+            maximise = FALSE;
+            floor_first = TRUE;
+            valid = FALSE; 
+        }
+
+        public void setObjective(float[] row, boolean maximize) {
+            for(int i=row.length-1; i>0; i--) row[i] = row[i-1];
+            row[0] = (float)0.0;
+            for(int j = 1; j <= columns; j++) {
+                int Row = 0;
+                int column = j;
+                float Value = row[j];
+                int elmnr, lastelm;
+                
+                if(Row > rows || Row < 0) throw new Error("row out of range");
+                if(column > columns || column < 1) throw new Error("column out of range");
+                
+                if (basis[column] == TRUE && Row > 0) basis_valid = FALSE;
+                eta_valid = FALSE;
+                elmnr = col_end[column-1];
+                while((elmnr < col_end[column]) ? (get_row_nr(mat, elmnr) != Row) : false) elmnr++;
+                if((elmnr != col_end[column]) ? (get_row_nr(mat, elmnr) == Row) : false ) {
+                    if (ch_sign[Row] != FALSE) set_value(mat, elmnr, -Value);
+                    else set_value(mat, elmnr, Value);
+                } else {
+                    /* check if more space is needed for matrix */
+                    if (non_zeros + 1 > mat_alloc) throw new Error("not enough mat space; this should not happen");
+                    /* Shift the matrix */
+                    lastelm=non_zeros; 
+                    for(int i = lastelm; i > elmnr ; i--) {
+                        set_row_nr(mat,i,get_row_nr(mat,i-1));
+                        set_value(mat,i,get_value(mat,i-1));
+                    }
+                    for(int i = column; i <= columns; i++) col_end[i]++;
+                    /* Set new element */
+                    set_row_nr(mat,elmnr, Row);
+                    if (ch_sign[Row] != FALSE) set_value(mat, elmnr, -Value);
+                    else set_value(mat, elmnr, Value);
+                    row_end_valid=FALSE;
+                    non_zeros++;
+                    if (active != FALSE) Non_zeros=non_zeros;
+                }      
+            }
+            if (maximize) {
+                if (maximise == FALSE) {
+                    for(int i = 0; i < non_zeros; i++)
+                        if(get_row_nr(mat, i)==0)
+                            set_value(mat, i, get_value(mat,i)* (float)-1.0);
+                    eta_valid=FALSE;
+                }
+                maximise=TRUE;
+                ch_sign[0]=TRUE;
+                if (active != FALSE) Maximise=TRUE;
+            } else {
+                if (maximise==TRUE) {
+                    for(int i = 0; i < non_zeros; i++)
+                        if(get_row_nr(mat, i)==0)
+                            set_value(mat, i, get_value(mat,i) * (float)-1.0);
+                    eta_valid=FALSE;
+                } 
+                maximise=FALSE;
+                ch_sign[0]=FALSE;
+                if (active != FALSE) Maximise=FALSE;
+            }
+        }
+
+        public void add_constraint(float[] row, short constr_type, float rh) {
+            for(int i=row.length-1; i>0; i--) row[i] = row[i-1];
+            row[0] = (float)0.0;
+
+            MatrixArray newmat;
+            int  elmnr;
+            int  stcol;
+
+            newmat = alternate_mat;
+            for(int i = 0; i < non_zeros; i++) { set_row_nr(newmat,i, 0); set_value(newmat, i, 0); }
+            for(int i = 1; i <= columns; i++) if (row[i]!=0) non_zeros++;
+            if (non_zeros > mat_alloc) throw new Error("not enough mat space; this should not happen");
+            rows++;
+            sum++;
+            if(rows > rows_alloc) throw new Error("not enough rows; this should never happen");
+            if(constr_type==GE) ch_sign[rows] = TRUE;
+            else ch_sign[rows] = FALSE;
+
+            elmnr = 0;
+            stcol = 0;
+            for(int i = 1; i <= columns; i++) {
+                for(int j = stcol; j < col_end[i]; j++) {  
+                    set_row_nr(newmat,elmnr, get_row_nr(mat, j));
+                    set_value(newmat, elmnr, get_value(mat,j));
+                    elmnr++;
+                }
+                if(((i>=1 && i< columns && row[i]!=0)?TRUE:FALSE) != FALSE) {
+                    if(ch_sign[rows] != FALSE) set_value(newmat, elmnr, -row[i]);
+                    else set_value(newmat, elmnr, row[i]);
+                    set_row_nr(newmat,elmnr, rows);
+                    elmnr++;
+                }
+                stcol=col_end[i];
+                col_end[i]=elmnr;
+            }    
+            
+            alternate_mat = mat;
+            mat = newmat;
+
+            for(int i = sum ; i > rows; i--) {
+                orig_upbo[i]=orig_upbo[i-1];
+                orig_lowbo[i]=orig_lowbo[i-1];
+                basis[i]=basis[i-1];
+                lower[i]=lower[i-1];
+            }
+
+            for(int i =  1 ; i <= rows; i++) if(bas[i] >= rows) bas[i]++;
+
+            if(constr_type==LE || constr_type==GE) orig_upbo[rows]=infinite;
+            else if(constr_type==EQ) orig_upbo[rows]=0;
+            else throw new Error("Wrong constraint type\n");
+            orig_lowbo[rows]=0;
+
+            if(constr_type==GE && rh != 0) orig_rh[rows]=-rh;
+            else orig_rh[rows]=rh;  
+
+            row_end_valid=FALSE;
+            bas[rows]=rows;
+            basis[rows]=TRUE;
+            lower[rows]=TRUE;   
+            if (active != FALSE) set_globals();
+            eta_valid=FALSE;
+        }
+
+        public void bound_sum(int column1, int column2, float bound, short type, float[] scratch) {
+            for(int i=0; i<scratch.length; i++) scratch[i] = (float)0.0;
+            scratch[column1] = (float)1.0;
+            scratch[column2] = (float)1.0;
+            add_constraint(scratch, type, bound);
+            for(int i=0; i<scratch.length; i++) scratch[i] = (float)0.0;
+        }
+
+        public void bound_difference(int column1, int column2, float bound, short type, float[] scratch) {
+            for(int i=0; i<scratch.length; i++) scratch[i] = (float)0.0;
+            scratch[column1] = (float)1.0;
+            scratch[column2] = (float)-1.0;
+            add_constraint(scratch, type, bound);
+            for(int i=0; i<scratch.length; i++) scratch[i] = (float)0.0;
+        }
+
+        public void set_upbo(int column, float value) {
+            if(column > columns || column < 1) throw new Error("column out of range");
+            if(value < orig_lowbo[rows + column]) throw new Error("UpperBound must be >= lowerBound"); 
+            eta_valid = FALSE;
+            orig_upbo[rows+column] = value;
+        }
+
+        public void set_lowbo(int column, float value) {
+            if(column > columns || column < 1) throw new Error("column out of range");
+            if(value > orig_upbo[rows + column]) throw new Error("UpperBound must be >= lowerBound"); 
+            eta_valid = FALSE;
+            orig_lowbo[rows+column] = value;
+        }
+
+        public void set_rh(int row, float value) {
+            if(row > rows || row < 0) throw new Error("Row out of Range");
+            if(row == 0) throw new Error("Warning: attempt to set RHS of objective function, ignored");
+            if (ch_sign[row] != FALSE) orig_rh[row] = -value;
+            else orig_rh[row] = value;
+            eta_valid = FALSE;
+        } 
+
+        public void set_rh_vec(float[] rh) {
+            for(int i=1; i <= rows; i++)
+                if (ch_sign[i] != FALSE) orig_rh[i]=-rh[i];
+                else orig_rh[i]=rh[i];
+            eta_valid=FALSE;
+        }
+
+
+        public void set_constr_type(int row, short con_type) {
+            if (row > rows || row < 1) throw new Error("Row out of Range");
+            switch(con_type) {
+                case EQ:
+                    orig_upbo[row]=0;
+                    basis_valid=FALSE;
+                    if (ch_sign[row] != FALSE) {
+                        for(int i = 0; i < non_zeros; i++)
+                            if (get_row_nr(mat, i)==row) set_value(mat, i, get_value(mat,i) * (float)-1);
+                        eta_valid=FALSE;
+                        ch_sign[row]=FALSE;
+                        if (orig_rh[row]!=0) orig_rh[row]*=-1;
+                    }
+                    break;
+                case LE:
+                    orig_upbo[row]=infinite;
+                    basis_valid=FALSE;
+                    if (ch_sign[row] != FALSE) {
+                        for(int i = 0; i < non_zeros; i++)
+                            if (get_row_nr(mat, i)==row) set_value(mat, i, get_value(mat,i) * (float)-1);
+                        eta_valid=FALSE;
+                        ch_sign[row]=FALSE;
+                        if (orig_rh[row]!=0) orig_rh[row]*=-1;
+                    }
+                    break;
+                case GE:
+                    orig_upbo[row]=infinite;
+                    basis_valid=FALSE;
+                    if (ch_sign[row] == FALSE) {
+                        for(int i = 0; i < non_zeros; i++)
+                            if (get_row_nr(mat, i)==row) set_value(mat, i, get_value(mat,i) * (float)-1);
+                        eta_valid=FALSE;
+                        ch_sign[row]=TRUE;
+                        if (orig_rh[row]!=0) orig_rh[row]*=-1;
+                    }
+                    break;
+                default: throw new Error("Constraint type not (yet) implemented");
+            }
+        }
+
+        void set_globals() {
+            Rows = rows;
+            columns = columns;
+            Sum = Rows + columns;
+            Non_zeros = non_zeros;
+            Mat = mat;
+            Col_no = col_no;
+            Col_end = col_end;
+            Row_end = row_end;
+            Rh = rh;
+            Rhs = rhs;
+            Orig_rh = orig_rh;
+            Orig_upbo = orig_upbo;
+            Orig_lowbo = orig_lowbo;
+            Upbo = upbo;
+            Lowbo = lowbo;
+            Bas = bas;
+            Basis = basis;
+            Lower = lower;
+            Eta_alloc = eta_alloc;
+            Eta_size = eta_size;
+            Num_inv = num_inv;
+            Eta_value = eta_value;
+            Eta_row_nr = eta_row_nr;
+            Eta_col_end = eta_col_end;
+            Solution = solution;
+            Best_solution = best_solution;
+            Infinite = infinite;
+            Epsilon = epsilon;
+            Epsb = epsb;
+            Epsd = epsd;
+            Epsel = epsel;
+            TREJ = TREJ;
+            TINV = TINV;
+            Maximise = maximise;
+            Floor_first = floor_first;
+            active = TRUE;
+        }
+
+        private void ftran(int start, int end, float[] pcol) {
+            int k, r;
+            float theta;
+            for(int i = start; i <= end; i++) {
+                k = Eta_col_end[i] - 1;
+                r = Eta_row_nr[k];
+                theta = pcol[r];
+                if (theta != 0) for(int j = Eta_col_end[i - 1]; j < k; j++)
+                    pcol[Eta_row_nr[j]] += theta * Eta_value[j];
+                pcol[r] *= Eta_value[k];
+            }
+            for(int i = 0; i <= Rows; i++) round(pcol[i], Epsel);
+        }
+
+        private void btran(float[] row) {
+            int k;
+            float f;
+            for(int i = Eta_size; i >= 1; i--) {
+                f = 0;
+                k = Eta_col_end[i] - 1;
+                for(int j = Eta_col_end[i - 1]; j <= k; j++) f += row[Eta_row_nr[j]] * Eta_value[j];
+                f = round(f, Epsel);
+                row[Eta_row_nr[k]] = f;
+            }
+        }
+
+        static int[] num = new int[65535];
+        static int[] rownum = new int[65535];
+        static int[] colnum = new int[65535];
+
+        short Isvalid() {
+            int row_nr;
+            if (row_end_valid == FALSE) {
+                for(int i = 0; i <= rows; i++) { num[i] = 0; rownum[i] = 0; }
+                for(int i = 0; i < non_zeros; i++) rownum[get_row_nr(mat, i)]++;
+                row_end[0] = 0;
+                for(int i = 1; i <= rows; i++) row_end[i] = row_end[i - 1] + rownum[i];
+                for(int i = 1; i <= columns; i++)
+                    for(int j = col_end[i - 1]; j < col_end[i]; j++) {
+                        row_nr = get_row_nr(mat, j);
+                        if (row_nr != 0) {
+                            num[row_nr]++;
+                            col_no[row_end[row_nr - 1] + num[row_nr]] = i;
+                        }
+                    }
+                row_end_valid = TRUE;
+            }
+            if (valid != FALSE) return(TRUE);
+            for(int i = 0; i <= rows; i++) rownum[i] = 0;
+            for(int i = 0; i <= columns; i++) colnum[i] = 0;
+            for(int i = 1 ; i <= columns; i++)
+                for(int j = col_end[i - 1]; j < col_end[i]; j++) {
+                    colnum[i]++;
+                    rownum[get_row_nr(mat, j)]++;
+                }
+            for(int i = 1; i <= columns; i++)
+                if (colnum[i] == 0)
+                    throw new Error("Warning: Variable " + i + " not used in any constaints\n");
+            valid = TRUE;
+            return(TRUE);
+        } 
+
+        private void resize_eta() {
+            Eta_alloc *= 2;
+            throw new Error("eta undersized; this should never happen");
+            /*
+            float[] db_ptr = Eta_value;
+            Eta_value = new float[Eta_alloc];
+            System.arraycopy(db_ptr, 0, Eta_value, 0, db_ptr.length);
+            eta_value = Eta_value;
+
+            int[] int_ptr = Eta_row_nr;
+            Eta_row_nr = new int[Eta_alloc];
+            System.arraycopy(int_ptr, 0, Eta_row_nr, 0, int_ptr.length);
+            eta_row_nr = Eta_row_nr;
+            */
+        }
+
+        private void condensecol(int row_nr, float[] pcol) {
+            int elnr;
+            elnr = Eta_col_end[Eta_size];
+            if (elnr + Rows + 2 > Eta_alloc) resize_eta();
+            for(int i = 0; i <= Rows; i++)
+                if (i != row_nr && pcol[i] != 0) {
+                    Eta_row_nr[elnr] = i;
+                    Eta_value[elnr] = pcol[i];
+                    elnr++;
+                }
+            Eta_row_nr[elnr] = row_nr;
+            Eta_value[elnr] = pcol[row_nr];
+            elnr++;
+            Eta_col_end[Eta_size + 1] = elnr;
+        }
+
+        private void addetacol() {
+            int k;
+            float theta;
+            int j = Eta_col_end[Eta_size];
+            Eta_size++;
+            k = Eta_col_end[Eta_size];
+            theta = 1 / (float) Eta_value[k - 1];
+            Eta_value[k - 1] = theta;
+            for(int i = j; i < k - 1; i++) Eta_value[i] *= -theta;
+            JustInverted = FALSE;
+        }
+
+        private void setpivcol(short lower,  int varin, float[]   pcol) {
+            int colnr;
+            float f;
+            if (lower != FALSE) f = 1;
+            else f = -1;
+            for(int i = 0; i <= Rows; i++) pcol[i] = 0;
+            if (varin > Rows) {
+                colnr = varin - Rows;
+                for(int i = Col_end[colnr - 1]; i < Col_end[colnr]; i++) pcol[get_row_nr(Mat, i)] = get_value(Mat,i) * f;
+                pcol[0] -= Extrad * f;
+            } else {
+                if (lower != FALSE) pcol[varin] = 1;
+                else pcol[varin] = -1;
+            }
+            ftran(1, Eta_size, pcol);
+        }
+
+        private void minoriteration(int colnr, int row_nr) {
+            int k, wk, varin, varout, elnr;
+            float piv = 0, theta;
+            varin = colnr + Rows;
+            elnr = Eta_col_end[Eta_size];
+            wk = elnr;
+            Eta_size++;
+            if (Extrad != 0) {
+                Eta_row_nr[elnr] = 0;
+                Eta_value[elnr] = -Extrad;
+                elnr++;
+            }
+            for(int j = Col_end[colnr - 1] ; j < Col_end[colnr]; j++) {
+                k = get_row_nr(Mat, j);
+                if (k == 0 && Extrad != 0) Eta_value[Eta_col_end[Eta_size -1]] += get_value(Mat,j);
+                else if (k != row_nr) {
+                    Eta_row_nr[elnr] = k;
+                    Eta_value[elnr] = get_value(Mat,j);
+                    elnr++;
+                } else {
+                    piv = get_value(Mat,j);
+                }
+            }
+            Eta_row_nr[elnr] = row_nr;
+            Eta_value[elnr] = 1 / (float) piv;
+            elnr++;
+            theta = Rhs[row_nr] / (float) piv;
+            Rhs[row_nr] = theta;
+            for(int i = wk; i < elnr - 1; i++) Rhs[Eta_row_nr[i]] -= theta * Eta_value[i];
+            varout = Bas[row_nr];
+            Bas[row_nr] = varin;
+            Basis[varout] = FALSE;
+            Basis[varin] = TRUE;
+            for(int i = wk; i < elnr - 1; i++) Eta_value[i] /= - (float) piv;
+            Eta_col_end[Eta_size] = elnr;
+        }
+
+        private void rhsmincol(float theta, int row_nr, int varin) {
+            int varout;
+            float f;
+            if (row_nr > Rows + 1) {
+                System.err.println("Error: rhsmincol called with row_nr: " + row_nr + ", rows: " + Rows + "\n");
+                System.err.println("This indicates numerical instability\n");
+            }
+            int j = Eta_col_end[Eta_size];
+            int k = Eta_col_end[Eta_size + 1];
+            for(int i = j; i < k; i++) {
+                f = Rhs[Eta_row_nr[i]] - theta * Eta_value[i];
+                f = round(f, Epsb);
+                Rhs[Eta_row_nr[i]] = f;
+            }
+            Rhs[row_nr] = theta;
+            varout = Bas[row_nr];
+            Bas[row_nr] = varin;
+            Basis[varout] = FALSE;
+            Basis[varin] = TRUE;
+        }
+
+        private static int[] rownum_ = new int[65535];
+        private static int[] colnum_ = new int[65535];
+        private static int[] col = new int[65535];
+        private static int[] row = new int[65535];
+        private static float[] pcol = new float[65535];
+        private static short[] frow = new short[65535];
+        private static short[] fcol = new short[65535];
+
+        void invert() {
+            int    v, wk, numit, varnr, row_nr, colnr, varin;
+            float    theta;
+
+            for(int i = 0; i <= Rows; i++) rownum_[i] = 0;
+            for(int i = 0; i <= Rows; i++) col[i] = 0;
+            for(int i = 0; i <= Rows; i++) row[i] = 0;
+            for(int i = 0; i <= Rows; i++) pcol[i] = 0;
+            for(int i = 0; i <= Rows; i++) frow[i] = TRUE;
+            for(int i = 0; i < columns; i++) fcol[i] = FALSE;
+            for(int i = 0; i <= columns; i++) colnum_[i] = 0;
+
+            for(int i = 0; i <= Rows; i++)
+                if (Bas[i] > Rows) fcol[Bas[i] - Rows - 1] = TRUE;
+                else frow[Bas[i]] = FALSE;
+
+            for(int i = 1; i <= Rows; i++)
+                if (frow[i] != FALSE)
+                    for(int j = Row_end[i - 1] + 1; j <= Row_end[i]; j++) {
+                        wk = Col_no[j];
+                        if (fcol[wk - 1] != FALSE) {
+                            colnum_[wk]++;
+                            rownum_[i - 1]++;
+                        }
+                    }
+
+            for(int i = 1; i <= Rows; i++) Bas[i] = i;
+            for(int i = 1; i <= Rows; i++) Basis[i] = TRUE;
+            for(int i = 1; i <= columns; i++) Basis[i + Rows] = FALSE;
+            for(int i = 0; i <= Rows; i++) Rhs[i] = Rh[i];
+            for(int i = 1; i <= columns; i++) {
+                varnr = Rows + i;
+                if (Lower[varnr] == FALSE) {
+                    theta = Upbo[varnr];
+                    for(int j = Col_end[i - 1]; j < Col_end[i]; j++)
+                        Rhs[get_row_nr(Mat, j)] -= theta * get_value(Mat,j);
+                }
+            }
+            for(int i = 1; i <= Rows; i++) if (Lower[i] == FALSE) Rhs[i] -= Upbo[i];
+            Eta_size = 0;
+            v = 0;
+            row_nr = 0;
+            Num_inv = 0;
+            numit = 0;
+            while(v < Rows) {
+                int j;
+                row_nr++;
+                if (row_nr > Rows) row_nr = 1;
+                v++;
+                if (rownum_[row_nr - 1] == 1)
+                    if (frow[row_nr] != FALSE) {
+                        v = 0;
+                        j = Row_end[row_nr - 1] + 1;
+                        while(fcol[Col_no[j] - 1] == FALSE) j++;
+                        colnr = Col_no[j];
+                        fcol[colnr - 1] = FALSE;
+                        colnum_[colnr] = 0;
+                        for(j = Col_end[colnr - 1]; j < Col_end[colnr]; j++)
+                            if (frow[get_row_nr(Mat, j)] != FALSE)
+                                rownum_[get_row_nr(Mat, j) - 1]--;
+                        frow[row_nr] = FALSE;
+                        minoriteration(colnr, row_nr);
+                    }
+            }
+            v = 0;
+            colnr = 0;
+            while(v < columns) {
+                int j;
+                colnr++;
+                if (colnr > columns) colnr = 1;
+                v++;
+                if (colnum_[colnr] == 1)
+                    if (fcol[colnr - 1] != FALSE) {
+                        v = 0;
+                        j = Col_end[colnr - 1] + 1;
+                        while(frow[get_row_nr(Mat, j - 1)] == FALSE) j++;
+                        row_nr = get_row_nr(Mat, j - 1);
+                        frow[row_nr] = FALSE;
+                        rownum_[row_nr - 1] = 0;
+                        for(j = Row_end[row_nr - 1] + 1; j <= Row_end[row_nr]; j++)
+                            if (fcol[Col_no[j] - 1] != FALSE)
+                                colnum_[Col_no[j]]--;
+                        fcol[colnr - 1] = FALSE;
+                        numit++;
+                        col[numit - 1] = colnr;
+                        row[numit - 1] = row_nr;
+                    }
+            }
+            for(int j = 1; j <= columns; j++)
+                if (fcol[j - 1] != FALSE) {
+                    fcol[j - 1] = FALSE;
+                    setpivcol(Lower[Rows + j], j + Rows, pcol);
+                    row_nr = 1;
+                    while((frow[row_nr] == FALSE || pcol[row_nr] == FALSE) && row_nr <= Rows)
+                        row_nr++; /* this sometimes sets row_nr to Rows + 1 and makes
+                                     rhsmincol crash. Solved in 2.0? MB */
+                    if (row_nr == Rows + 1) throw new Error("Inverting failed");
+                    frow[row_nr] = FALSE;
+                    condensecol(row_nr, pcol);
+                    theta = Rhs[row_nr] / (float) pcol[row_nr];
+                    rhsmincol(theta, row_nr, Rows + j);
+                    addetacol();
+                }
+            for(int i = numit - 1; i >= 0; i--) {
+                colnr = col[i];
+                row_nr = row[i];
+                varin = colnr + Rows;
+                for(int j = 0; j <= Rows; j++) pcol[j] = 0;
+                for(int j = Col_end[colnr - 1]; j < Col_end[colnr]; j++) pcol[get_row_nr(Mat, j)] = get_value(Mat,j);
+                pcol[0] -= Extrad;
+                condensecol(row_nr, pcol);
+                theta = Rhs[row_nr] / (float) pcol[row_nr];
+                rhsmincol(theta, row_nr, varin);
+                addetacol();
+            }
+            for(int i = 1; i <= Rows; i++) Rhs[i] = round(Rhs[i], Epsb);
+            JustInverted = TRUE;
+            DoInvert = FALSE;
+        }
+
+        private short colprim(Ref colnr, short minit, float[]   drow) {
+            int  varnr;
+            float f, dpiv;
+              dpiv = -Epsd;
+            colnr.value = 0;
+            if (minit == FALSE) {
+                for(int i = 1; i <= Sum; i++) drow[i] = 0;
+                drow[0] = 1;
+                btran(drow);
+                for(int i = 1; i <= columns; i++) {
+                    varnr = Rows + i;
+                    if (Basis[varnr] == FALSE)
+                        if (Upbo[varnr] > 0) {
+                            f = 0;
+                            for(int j = Col_end[i - 1]; j < Col_end[i]; j++) f += drow[get_row_nr(Mat, j)] * get_value(Mat,j);
+                            drow[varnr] = f;
+                        }
+                }
+                for(int i = 1; i <= Sum; i++) drow[i] = round(drow[i], Epsd);
+            }
+            for(int i = 1; i <= Sum; i++)
+                if (Basis[i] == FALSE)
+                    if (Upbo[i] > 0) {
+                        if (Lower[i] != FALSE) f = drow[i];
+                        else f = -drow[i];
+                        if (f < dpiv) {
+                            dpiv = f;
+                            colnr.value = i;
+                        }
+                    }
+            if (colnr.value == 0) {
+                Doiter   = FALSE;
+                DoInvert = FALSE;
+                Status   = OPTIMAL;
+            }
+            return(colnr.value > 0 ? (short)1 : (short)0);
+        }
+
+        private short rowprim(int colnr, Ref row_nr, Ref theta, float[] pcol) {
+            float f = 0, quot; 
+            row_nr.value = 0;
+            theta.value = Infinite;
+            for(int i = 1; i <= Rows; i++) {
+                f = pcol[i];
+                if (Math.abs(f) < TREJ) f = 0;
+                if (f != 0) {
+                    quot = 2 * Infinite;
+                    if (f > 0) quot = Rhs[i] / (float) f;
+                    else if (Upbo[Bas[i]] < Infinite) quot = (Rhs[i] - Upbo[Bas[i]]) / (float) f;
+                    round(quot, Epsel);
+                    if (quot < theta.value) {
+                        theta.value = quot;
+                        row_nr.value = i;
+                    }
+                }
+            }
+            if (row_nr.value == 0)  
+                for(int i = 1; i <= Rows; i++) {
+                    f = pcol[i];
+                    if (f != 0) {
+                        quot = 2 * Infinite;
+                        if (f > 0) quot = Rhs[i] / (float) f;
+                        else if (Upbo[Bas[i]] < Infinite) quot = (Rhs[i] - Upbo[Bas[i]]) / (float) f;
+                        quot = round(quot, Epsel);
+                        if (quot < theta.value) {
+                            theta.value = quot;
+                            row_nr.value = i;
+                        }
+                    }
+                }
+
+            if (theta.value < 0) throw new Error("Warning: Numerical instability, qout = " + theta.value);
+            if (row_nr.value == 0) {
+                if (Upbo[colnr] == Infinite) {
+                    Doiter   = FALSE;
+                    DoInvert = FALSE;
+                    Status   = UNBOUNDED;
+                } else {
+                    int i = 1;
+                    while(pcol[i] >= 0 && i <= Rows) i++;
+                    if (i > Rows) {
+                        Lower[colnr] = FALSE;
+                        Rhs[0] += Upbo[colnr]*pcol[0];
+                        Doiter = FALSE;
+                        DoInvert = FALSE;
+                    } else if (pcol[i]<0) {
+                        row_nr.value = i;
+                    }
+                }
+            }
+            if (row_nr.value > 0) Doiter = TRUE;
+            return((row_nr.value > 0) ? (short)1 : (short)0);
+        }
+
+        private short rowdual(Ref row_nr) {
+            int   i;
+            float  f, g, minrhs;
+            short artifs;
+            row_nr.value = 0;
+            minrhs = -Epsb;
+            i = 0;
+            artifs = FALSE;
+            while(i < Rows && artifs == FALSE) {
+                i++;
+                f = Upbo[Bas[i]];
+                if (f == 0 && (Rhs[i] != 0)) {
+                    artifs = TRUE;
+                    row_nr.value = i;
+                } else {
+                    if (Rhs[i] < f - Rhs[i]) g = Rhs[i];
+                    else g = f - Rhs[i];
+                    if (g < minrhs) {
+                        minrhs = g;
+                        row_nr.value = i;
+                    }
+                }
+            }
+            return(row_nr.value > 0 ? (short)1 : (short)0);
+        }
+
+        private short coldual(int row_nr, Ref colnr, short minit, float[] prow, float[] drow) {
+            int r, varnr;
+            float theta, quot, pivot, d, f, g;
+            Doiter = FALSE;
+            if (minit == FALSE) {
+                for(int i = 0; i <= Rows; i++) {
+                    prow[i] = 0;
+                    drow[i] = 0;
+                }
+                drow[0] = 1;
+                prow[row_nr] = 1;
+                for(int i = Eta_size; i >= 1; i--) {
+                    d = 0;
+                    f = 0;
+                    r = Eta_row_nr[Eta_col_end[i] - 1];
+                    for(int j = Eta_col_end[i - 1]; j < Eta_col_end[i]; j++) {
+                        /* this is where the program consumes most cpu time */
+                        f += prow[Eta_row_nr[j]] * Eta_value[j];
+                        d += drow[Eta_row_nr[j]] * Eta_value[j];
+                    }
+                    f = round(f, Epsel);
+                    prow[r] = f;
+                    d = round(d, Epsel);
+                    drow[r] = d;
+                }
+                for(int i = 1; i <= columns; i++) {
+                    varnr = Rows + i;
+                    if (Basis[varnr] == FALSE) {
+                        d = - Extrad * drow[0];
+                        f = 0;
+                        for(int j = Col_end[i - 1]; j < Col_end[i]; j++) {
+                            d = d + drow[get_row_nr(Mat, j)] * get_value(Mat,j);
+                            f = f + prow[get_row_nr(Mat, j)] * get_value(Mat,j);
+                        }
+                        drow[varnr] = d;
+                        prow[varnr] = f;
+                    }
+                }
+                for(int i = 0; i <= Sum; i++) {
+                    prow[i] = round(prow[i], Epsel);
+                    drow[i] = round(drow[i], Epsd);
+                }
+            }
+            if (Rhs[row_nr] > Upbo[Bas[row_nr]]) g = -1;
+            else g = 1;
+            pivot = 0;
+            colnr.value = 0;
+            theta = Infinite;
+            for(int i = 1; i <= Sum; i++) {
+                if (Lower[i] != FALSE) d = prow[i] * g;
+                else d = -prow[i] * g;
+                if ((d < 0) && (Basis[i] == FALSE) && (Upbo[i] > 0)) {
+                    if (Lower[i] == FALSE) quot = -drow[i] / (float) d;
+                    else quot = drow[i] / (float) d;
+                    if (quot < theta) {
+                        theta = quot;
+                        pivot = d;
+                        colnr.value = i;
+                    } else if ((quot == theta) && (Math.abs(d) > Math.abs(pivot))) {
+                        pivot = d;
+                        colnr.value = i;
+                    }
+                }
+            }
+            if (colnr.value > 0) Doiter = TRUE;
+            return(colnr.value > 0 ? (short)1 : (short)0);
+        }
+
+        private void iteration(int row_nr, int varin, Ref theta, float up, Ref minit, Ref low, short primal,float[] pcol) {
+            int k, varout;
+            float f;
+            float pivot;
+            iter++;
+            minit.value = theta.value > (up + Epsb) ? 1 : 0;
+            if (minit.value != 0) {
+                theta.value = up;
+                low.value = low.value == 0 ? 1 : 0;
+            }
+            k = Eta_col_end[Eta_size + 1];
+            pivot = Eta_value[k - 1];
+            for(int i = Eta_col_end[Eta_size]; i < k; i++) {
+                f = Rhs[Eta_row_nr[i]] - theta.value * Eta_value[i];
+                f = round(f, Epsb);
+                Rhs[Eta_row_nr[i]] = f;
+            }
+            if (minit.value == 0) {
+                Rhs[row_nr] = theta.value;
+                varout = Bas[row_nr];
+                Bas[row_nr] = varin;
+                Basis[varout] = FALSE;
+                Basis[varin] = TRUE;
+                if (primal != FALSE && pivot < 0) Lower[varout] = FALSE;
+                if (low.value == 0 && up < Infinite) {
+                    low.value = TRUE;
+                    Rhs[row_nr] = up - Rhs[row_nr];
+                    for(int i = Eta_col_end[Eta_size]; i < k; i++) Eta_value[i] = -Eta_value[i];
+                }
+                addetacol();
+                Num_inv++;
+            }
+        }
+
+        static float[] drow = new float[65535];
+        static float[] prow = new float[65535];
+        static float[] Pcol = new float[65535];
+
+        private int solvelp() {
+            int    varnr;
+            float   f = 0, theta = 0;
+            short  primal;
+            short  minit;
+            int    colnr, row_nr;
+            colnr = 0;
+            row_nr = 0;
+            short flag; 
+            Ref ref1, ref2, ref3;
+            ref1 = new Ref(0);
+            ref2 = new Ref(0);
+            ref3 = new Ref(0);
+
+            for(int i = 0; i <= Sum; i++) { drow[i] = 0; prow[i] = 0; }
+            for(int i = 0; i <= Rows; i++) Pcol[i] = 0;
+            iter = 0;
+            minit = FALSE;
+            Status = RUNNING;
+            DoInvert = FALSE;
+            Doiter = FALSE;
+            primal = TRUE;
+            for(int i = 0; i != Rows && primal != FALSE;) {
+                i++;
+                primal = (Rhs[i] >= 0 && Rhs[i] <= Upbo[Bas[i]]) ? (short)1: (short)0;
+            }
+            if (primal == FALSE) {
+                drow[0] = 1;
+                for(int i = 1; i <= Rows; i++) drow[i] = 0;
+                Extrad = 0;
+                for(int i = 1; i <= columns; i++) {
+                    varnr = Rows + i;
+                    drow[varnr] = 0;
+                    for(int j = Col_end[i - 1]; j < Col_end[i]; j++)
+                        if (drow[get_row_nr(Mat, j)] != 0)
+                            drow[varnr] += drow[get_row_nr(Mat, j)] * get_value(Mat,j);
+                    if (drow[varnr] < Extrad) Extrad = drow[varnr];
+                }
+            } else {
+                Extrad = 0;
+            }
+            minit = FALSE;
+            while(Status == RUNNING) {
+                Doiter = FALSE;
+                DoInvert = FALSE;
+                construct_solution(Solution);
+                if (primal != FALSE) {
+                    ref1.value = colnr;
+                    flag = colprim(ref1, minit, drow);
+                    colnr = (int)ref1.value;
+                    if (flag != FALSE) {
+                        setpivcol(Lower[colnr], colnr, Pcol);
+                        ref1.value = row_nr;
+                        ref2.value = theta;
+                        flag = rowprim(colnr, ref1, ref2, Pcol);
+                        row_nr = (int)ref1.value;
+                        theta = ref2.value;
+                        if (flag != FALSE) condensecol(row_nr, Pcol);
+                    }
+                } else {
+                    if (minit == FALSE) {
+                        ref1.value = row_nr;
+                        flag = rowdual(ref1);
+                        row_nr = (int)ref1.value;
+                    }
+                    if (row_nr > 0) {
+                        ref1.value = colnr;
+                        flag = coldual(row_nr, ref1, minit, prow, drow);
+                        colnr = (int)ref1.value;
+                        if (flag != FALSE) {
+                            setpivcol(Lower[colnr], colnr, Pcol);
+                            /* getting div by zero here ... MB */
+                            if (Pcol[row_nr] == 0) {
+                                throw new Error("An attempt was made to divide by zero (Pcol[" + row_nr + "])");
+                            } else {
+                                condensecol(row_nr, Pcol);
+                                f = Rhs[row_nr] - Upbo[Bas[row_nr]];
+                                if (f > 0) {
+                                    theta = f / (float) Pcol[row_nr];
+                                    if (theta <= Upbo[colnr])
+                                        Lower[Bas[row_nr]] = (Lower[Bas[row_nr]] == FALSE)? (short)1:(short)0;
+                                } else theta = Rhs[row_nr] / (float) Pcol[row_nr];
+                            }
+                        } else Status = INFEASIBLE;
+                    } else {
+                        primal   = TRUE;
+                        Doiter   = FALSE;
+                        Extrad   = 0;
+                        DoInvert = TRUE;
+                    }    
+                }
+                if (Doiter != FALSE) {
+                    ref1.value = theta;
+                    ref2.value = minit;
+                    ref3.value = Lower[colnr];
+                    iteration(row_nr, colnr, ref1, Upbo[colnr], ref2, ref3, primal, Pcol);
+                    theta = ref1.value;
+                    minit = (short)ref2.value;
+                    Lower[colnr] = (short)ref3.value;
+                }
+                if (Num_inv >= max_num_inv) DoInvert = TRUE;
+                if (DoInvert != FALSE) invert();
+            } 
+            total_iter += iter;
+            return(Status);
+        }
+
+        private void construct_solution(float[]   sol) {
+            float   f;
+            int basi;
+            for(int i = 0; i <= Rows; i++) sol[i] = 0;
+            for(int i = Rows + 1; i <= Sum; i++) sol[i] = Lowbo[i];
+            for(int i = 1; i <= Rows; i++) {
+                basi = Bas[i];
+                if (basi > Rows) sol[basi] += Rhs[i];
+            }
+            for(int i = Rows + 1; i <= Sum; i++)
+                if (Basis[i] == FALSE && Lower[i] == FALSE)
+                    sol[i] += Upbo[i];
+            for(int j = 1; j <= columns; j++) {
+                f = sol[Rows + j];
+                if (f != 0)
+                    for(int i = Col_end[j - 1]; i < Col_end[j]; i++)
+                        sol[get_row_nr(Mat, i)] += f * get_value(Mat,i);
+            }
+            for(int i = 0; i <= Rows; i++) {
+                if (Math.abs(sol[i]) < Epsb) sol[i] = 0;
+                else if (ch_sign[i] != FALSE) sol[i] = -sol[i];
+            }
+        }
+
+        private void calculate_duals() {
+            for(int i = 1; i <= Rows; i++) duals[i] = 0;
+            duals[0] = 1;
+            btran(duals);
+            for(int i = 1; i <= Rows; i++) {
+                if (basis[i] != FALSE) duals[i] = 0;
+                else if ( ch_sign[0] == ch_sign[i]) duals[i] = -duals[i];
+            }
+        }
+
+        private static Random rdm = new Random();
+
+        private int milpsolve(float[]   upbo, float[]   lowbo, short[]  sbasis, short[]  slower, int[]    sbas) {
+            int failure, notint, is_worse;
+            float theta, tmpfloat;
+            notint = 0;
+
+            if (Break_bb != FALSE) return(BREAK_BB);
+            Level++;
+            total_nodes++;
+            if (Level > max_level) max_level = Level;
+            System.arraycopy(upbo, 0, Upbo, 0, Sum + 1);
+            System.arraycopy(lowbo, 0, Lowbo, 0, Sum + 1);
+            System.arraycopy(sbasis, 0, Basis, 0, Sum + 1);
+            System.arraycopy(slower, 0, Lower, 0, Sum + 1);
+            System.arraycopy(sbas, 0, Bas, 0, Rows + 1);
+            System.arraycopy(Orig_rh, 0, Rh, 0, Rows + 1);
+            if (eta_valid == FALSE) {
+                for(int i = 1; i <= columns; i++)
+                    if (Lowbo[Rows + i] != 0) {
+                        theta = Lowbo[ Rows + i];
+                        if (Upbo[Rows + i]<Infinite) Upbo[Rows + i] -= theta;
+                        for(int j = Col_end[i - 1]; j < Col_end[i]; j++) Rh[get_row_nr(Mat, j)] -= theta * get_value(Mat,j);
+                    }
+                invert();
+                eta_valid = TRUE;
+            }
+            failure = solvelp();
+            if (failure == OPTIMAL) {
+                construct_solution(Solution);
+                /* if this solution is worse than the best sofar, this branch must die */
+                if (Maximise != FALSE) is_worse = (Solution[0] <= Best_solution[0]) ? 1:0;
+                else is_worse = (Solution[0] >= Best_solution[0]) ? 1:0;
+                if (is_worse != FALSE) {
+                    Level--;
+                    return(MILP_FAIL);
+                }
+                /* check if solution contains enough ints */
+                if (bb_rule == FIRST_NI) {
+                    notint = 0;
+                    int i = Rows + 1;
+                    while(i <= Sum && notint == 0) i++;
+                }
+                if (bb_rule == RAND_NI) {
+                    int nr_not_int, select_not_int;
+                    nr_not_int = 0;
+                    for(int i = Rows + 1; i <= Sum; i++)
+                        if (nr_not_int == 0) notint = 0;
+                        else {
+                            select_not_int=(rdm.nextInt() % nr_not_int) + 1;
+                            i = Rows + 1;
+                            while(select_not_int > 0) i++;
+                            notint = i - 1;
+                        }
+                }
+                if (notint != FALSE) throw new Error("integer linear programming not supported");
+                if (Maximise != FALSE) is_worse = (Solution[0] < Best_solution[0]) ? 1:0;
+                else is_worse = (Solution[0] > Best_solution[0]) ? 1:0;
+                if (is_worse == FALSE) {
+                    System.arraycopy(Solution, 0, Best_solution, 0, Sum + 1);
+                    calculate_duals();
+                    if (break_at_int != FALSE) {
+                        if (Maximise != FALSE &&  (Best_solution[0] > break_value)) Break_bb = TRUE;
+                        if (Maximise == FALSE &&  (Best_solution[0] < break_value)) Break_bb = TRUE;
+                    }
+                }
+            }
+            Level--;
+            return(failure);
+        }
+
+        public int solve() {
+            int result;
+            if (active == FALSE) set_globals();
+            total_iter  = 0;
+            max_level   = 1;
+            total_nodes = 0;
+            if (Isvalid() != FALSE) {
+                if (Maximise != FALSE && obj_bound == Infinite) Best_solution[0]=-Infinite;
+                else if (Maximise == FALSE && obj_bound==-Infinite) Best_solution[0] = Infinite;
+                else Best_solution[0] = obj_bound;
+                Level = 0;
+                if (basis_valid == FALSE) {
+                    for(int i = 0; i <= rows; i++) {
+                        basis[i] = TRUE;
+                        bas[i] = i;
+                    }
+                    for(int i = rows+1; i <= sum; i++) basis[i] = FALSE;
+                    for(int i = 0; i <= sum; i++) lower[i] = TRUE;
+                    basis_valid = TRUE;
+                }
+                eta_valid = FALSE;
+                Break_bb      = FALSE;
+                result        = milpsolve(Orig_upbo, Orig_lowbo, Basis, Lower, Bas); 
+                eta_size  = Eta_size;
+                eta_alloc = Eta_alloc;
+                num_inv   = Num_inv;
+                return(result);
+            }
+            return(FAILURE);
+        }
+
+    private final static float round( float val, float eps) { return (Math.abs(val) < eps) ? 0 : val; }
+    static int get_row_nr(MatrixArray m, int i) { return m.row_nr[i]; }
+    static void set_row_nr(MatrixArray m, int i, int val) { m.row_nr[i] = val; }
+    static float get_value(MatrixArray m, int i) { return m.value[i]; }
+    static void set_value(MatrixArray m, int i, float val) { m.value[i] = val; }
+    public static class MatrixArray {
+        public int[] row_nr;
+        public float[] value;
+        public final int length;
+        public MatrixArray(int length) { row_nr = new int[length]; value = new float[length]; this.length = length; }
+    }
+
+}
+