CheckVariableEqLs (1/a != 0 && a != 0) -> a != 0

dharmatech · Jun 15, 2015 · 287c61e · 287c61e
1 parent de4bede
commit 287c61e
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Showing 2 changed files with 16 additions and 4 deletions.
diff --git a/Symbolism/EliminateVariable.cs b/Symbolism/EliminateVariable.cs
@@ -13,8 +13,20 @@ public static class Extensions
     {
         public static MathObject CheckVariableEqLs(this List<Equation> eqs, Symbol sym)
         {
+            // (a == 10, a == 0)   ->   10 == 0   ->   false
+
             if (eqs.EliminateVariableEqLs(sym) == false) return false;
 
+            // (1/a != 0  &&  a != 0)   ->   a != 0
+
+            if (eqs.Any(eq => eq.Operator == Equation.Operators.NotEqual && eq.a == sym && eq.b == 0)
+                &&
+                eqs.Any(eq => eq.Operator == Equation.Operators.NotEqual && eq.a == 1 / sym && eq.b == 0))
+                return eqs
+                    .Where(eq => (eq.Operator == Equation.Operators.NotEqual && eq.a == 1 / sym && eq.b == 0) == false)
+                    .ToList()
+                    .CheckVariableEqLs(sym);
+
             return new And() { args = eqs.Select(eq => eq as MathObject).ToList() };
         }
 

diff --git a/Tests/Tests.cs b/Tests/Tests.cs
@@ -1228,25 +1228,25 @@ static void Main(string[] args)
                         new Or(
                             new And(
                                 vyB == -1 * ay * sqrt(2 * (ay ^ -1) * ((ay ^ -1) / 2 * (vyA ^ 2) + -1 * yA + yB)),
-                                (ay ^ -1) != 0,
+                                // (ay ^ -1) != 0,
                                 vxA != 0,
                                 ay != 0),
                             new And(
                                 vyB == ay * sqrt(2 * (ay ^ -1) * ((ay ^ -1) / 2 * (vyA ^ 2) + -1 * yA + yB)),
-                                (ay ^ -1) != 0,
+                                // (ay ^ -1) != 0,
                                 vxA != 0,
                                 ay != 0)))
                     .SubstituteEqLs(zeros)
                     .AssertEqTo(
                         new Or(
                           new And(
                               vyB == -ay * sqrt(-2 / ay * yA),
-                              1 / ay != 0,
+                              // 1 / ay != 0,
                               vxA != 0,
                               ay != 0),
                           new And(
                               vyB == ay * sqrt(-2 / ay * yA),
-                              1 / ay != 0,
+                              // 1 / ay != 0,
                               vxA != 0,
                               ay != 0)))
                     .SubstituteEqLs(vals)