added quadratic equation solving to Solver module, s/private/protected/

git-svn-id: svn://anubis/gvsu@362 45c1a28c-8058-47b2-ae61-ca45b979098e

cs658/final/util/Solver.cc

@@ -1,17 +1,43 @@
 
 #include "Solver.h"
+#include <math.h>
 
 Solver::Solver(double a, double b, double c, double d, double e)
 {
-    m_coef[0] = a;
+    this->a = a;
-    m_coef[1] = b;
+    this->b = b;
-    m_coef[2] = c;
+    this->c = c;
-    m_coef[3] = d;
+    this->d = d;
-    m_coef[4] = e;
+    this->e = e;
 }
 
+/* solve a quadratic equation */
 Solver::Result QuadraticSolver::solve()
 {
+    Result res;
+    double discriminant = b * b - 4 * a * c;
+    if (discriminant < 0.0)
+    {
+        res.numResults = 0;
+    }
+    else
+    {
+        double sqrt_discriminant = sqrt(discriminant);
+        double two_a = 2.0 * a;
+        if (sqrt_discriminant = 0.0)
+        {
+            res.numResults = 1;
+            res.results[0] = (-b) / two_a;
+        }
+        else
+        {
+            res.numResults = 2;
+            res.results[0] = (-b - sqrt_discriminant) / two_a;
+            res.results[1] = (-b + sqrt_discriminant) / two_a;
+        }
+    }
+
+    return res;
 }
 
 Solver::Result CubicSolver::solve()

cs658/final/util/Solver.h

@@ -18,8 +18,8 @@ class Solver
                double e = 0.0);
         virtual Result solve() = 0;
 
-    private:
+    protected:
-        double m_coef[5];
+        double a, b, c, d, e;
 };
 
 class QuadraticSolver : public Solver