From 9e8c5ac5d685aef9224289a5bac530250aee7298 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+git@gmail.com>
Date: Sat, 23 Apr 2011 22:23:07 -0400
Subject: [PATCH] Sketch: only attempt to solve if #vars == #equs

---
 Sketch.py | 50 +++++++++++++++++++++++++++-----------------------
 1 file changed, 27 insertions(+), 23 deletions(-)

diff --git a/Sketch.py b/Sketch.py
index f6fc82a..3b7a4c2 100644
--- a/Sketch.py
+++ b/Sketch.py
@@ -6,6 +6,8 @@ class Sketch(object):
     def __init__(self):
         self.shapes = []
         self.constraints = []
+        self.num_variables = 0
+        self.num_constraints = 0
 
     def __iter__(self):
         return self.shapes.__iter__()
@@ -28,26 +30,28 @@ class Sketch(object):
                     shape_vars[shape_var] = varid
                     varid += 1
                     varid_to_shape_var.append(shape_var)
-        dim = len(equations)
-        if len(shape_vars) > dim:
-            dim = len(shape_vars)
-        equs = []
-        variables = oovars(dim)
-        for e in equations:
-            coeffs = e[0]
-            equ = -e[1]
-            for c in coeffs:
-                equ = c[0] * variables[shape_vars[c[1]]] + equ
-            equs.append(equ)
-        if len(equs) < dim:
-            print 'TODO: pad equation list: %d equations, %d vars' % \
-                    (len(equs), len(variables))
-        s = sle(equs)
-        r = s.solve()
-        if r.ff != float('inf'):
-            print "SOLVED: ", r(variables)
-            for i in range(len(variables)):
-                varid_to_shape_var[i][0].setVar(varid_to_shape_var[i][1],
-                        r(variables[i]))
-            for s in self.shapes:
-                print 'shape:', repr(s.vars)
+        self.num_constraints = len(equations)
+        self.num_variables = len(shape_vars)
+        dim = self.num_constraints
+        if self.num_variables > dim:
+            dim = self.num_variables
+        if self.num_variables == self.num_constraints:
+            sle_equs = []
+            variables = oovars(dim)
+            for e in equations:
+                coeffs = e[0]
+                equ = -e[1]
+                for c in coeffs:
+                    equ = c[0] * variables[shape_vars[c[1]]] + equ
+                sle_equs.append(equ)
+            s = sle(sle_equs)
+            r = s.solve()
+            if r.ff != float('inf'):
+                print "SOLVED: ", r(variables)
+                for i in range(len(variables)):
+                    varid_to_shape_var[i][0].setVar(varid_to_shape_var[i][1],
+                            r(variables[i]))
+                for s in self.shapes:
+                    print 'shape:', repr(s.vars)
+                return True
+        return False