checkpoint

[anneal.git] / src / edu / berkeley / qfat / geom / Matrix.java

diff --git a/src/edu/berkeley/qfat/geom/Matrix.java b/src/edu/berkeley/qfat/geom/Matrix.java
index dda8285..c2419d6 100644 (file)
--- a/src/edu/berkeley/qfat/geom/Matrix.java
+++ b/src/edu/berkeley/qfat/geom/Matrix.java
@@ -366,4 +366,23 @@ public class Matrix {
         return z.times(p).times(m);
     }
 
         return z.times(p).times(m);
     }
 

+    /** returns the constraint-conjunction "(forall v)Mv=v" */
+    public AffineConstraint getAffineConstraint(float epsilon) {
+        AffineConstraint c1 = getAffineConstraint(a-1, b,   c,   d  , epsilon);
+        AffineConstraint c2 = getAffineConstraint(e,   f-1, g,   h  , epsilon);
+        AffineConstraint c3 = getAffineConstraint(i,   j,   k-1, l  , epsilon);
+        // FIXME: bottom row constraint?
+        return c1.intersect(c2.intersect(c3, epsilon), epsilon);
+    }
+
+    /** the AffineConstraint representing ax+by+cz+d=0 */
+    private static AffineConstraint getAffineConstraint(float a, float b, float c, float d, float epsilon) {
+        a = Math.abs(a) <= epsilon ? 0 : a;
+        b = Math.abs(b) <= epsilon ? 0 : b;
+        c = Math.abs(c) <= epsilon ? 0 : c;
+        d = Math.abs(d) <= epsilon ? 0 : d;
+        if (a!=0 || b!=0 || c!=0) return new Plane(a, b, c, d);
+        if (d==0) return new AffineConstraint.All();
+        return new AffineConstraint.Nothing();
+    }

 }
 }