added LinearSolver to util/Solver module; added shapes/Plane module

git-svn-id: svn://anubis/fart/trunk@59 7f9b0f55-74a9-4bce-be96-3c2cd072584d

util/Solver.cc

@@ -13,6 +13,40 @@ Solver::Solver(double a, double b, double c, double d, double e)
 }
 
 
+/**************************************************************************
+ * LinearSolver methods                                                   *
+ *************************************************************************/
+LinearSolver::LinearSolver(double a, double b)
+    : Solver(a, b)
+{
+}
+
+/* solve a linear equation */
+Solver::Result LinearSolver::solve()
+{
+    /* equation ax + b = 0 */
+    Result res;
+    if (a == 0.0)
+    {
+        if (b == 0.0)
+        {
+            res.numResults = 1;
+            res.results[0] = 0.0;
+        }
+        else
+        {
+            res.numResults = 0;
+        }
+    }
+    else
+    {
+        res.numResults = 1;
+        res.results[0] = -b / a;
+    }
+    return res;
+}
+
+
 /**************************************************************************
  * QuadraticSolver methods                                                *
  *************************************************************************/

util/Solver.h

@@ -24,6 +24,13 @@ class Solver
         double a, b, c, d, e;
 };
 
+class LinearSolver : public Solver
+{
+    public:
+        LinearSolver(double a, double b);
+        Result solve();
+};
+
 class QuadraticSolver : public Solver
 {
     public: