1 files changed, 103 insertions, 0 deletions
diff --git a/gsl-1.9/poly/zsolve_quadratic.c b/gsl-1.9/poly/zsolve_quadratic.c
new file mode 100644
index 0000000..dcdeec0
--- /dev/null
+++ b/gsl-1.9/poly/zsolve_quadratic.c
@@ -0,0 +1,103 @@
+/* poly/zsolve_quadratic.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/* complex_solve_quadratic.c - finds complex roots of a x^2 + b x + c = 0 */
+
+#include <config.h>
+#include <math.h>
+#include <gsl/gsl_complex.h>
+#include <gsl/gsl_poly.h>
+
+int
+gsl_poly_complex_solve_quadratic (double a, double b, double c,
+                                  gsl_complex *z0, gsl_complex *z1)
+{
+  double disc = b * b - 4 * a * c;
+
+  if (a == 0) /* Handle linear case */
+    {
+      if (b == 0)
+        {
+          return 0;
+        }
+      else
+        {
+          GSL_REAL(*z0) = -c / b;
+          GSL_IMAG(*z0) = 0;
+          return 1;
+        };
+    }
+
+  if (disc > 0)
+    {
+      if (b == 0)
+        {
+          double s = fabs (0.5 * sqrt (disc) / a);
+          GSL_REAL (*z0) = -s;
+          GSL_IMAG (*z0) = 0;
+          GSL_REAL (*z1) = s;
+          GSL_IMAG (*z1) = 0;
+        }
+      else
+        {
+          double sgnb = (b > 0 ? 1 : -1);
+          double temp = -0.5 * (b + sgnb * sqrt (disc));
+          double r1 = temp / a;
+          double r2 = c / temp;
+
+          if (r1 < r2)
+            {
+              GSL_REAL (*z0) = r1;
+              GSL_IMAG (*z0) = 0;
+              GSL_REAL (*z1) = r2;
+              GSL_IMAG (*z1) = 0;
+            }
+          else
+            {
+              GSL_REAL (*z0) = r2;
+              GSL_IMAG (*z0) = 0;
+              GSL_REAL (*z1) = r1;
+              GSL_IMAG (*z1) = 0;
+            }
+        }
+      return 2;
+    }
+  else if (disc == 0)
+    {
+      GSL_REAL (*z0) = -0.5 * b / a;
+      GSL_IMAG (*z0) = 0;
+
+      GSL_REAL (*z1) = -0.5 * b / a;
+      GSL_IMAG (*z1) = 0;
+
+      return 2;
+    }
+  else
+    {
+      double s = fabs (0.5 * sqrt (-disc) / a);
+
+      GSL_REAL (*z0) = -0.5 * b / a;
+      GSL_IMAG (*z0) = -s;
+
+      GSL_REAL (*z1) = -0.5 * b / a;
+      GSL_IMAG (*z1) = s;
+
+      return 2;
+    }
+}