1 files changed, 40 insertions, 0 deletions
diff --git a/gsl-1.9/doc/examples/demo_fn.c b/gsl-1.9/doc/examples/demo_fn.c
new file mode 100644
index 0000000..4d8a552
--- /dev/null
+++ b/gsl-1.9/doc/examples/demo_fn.c
@@ -0,0 +1,40 @@
+double
+quadratic (double x, void *params)
+{
+  struct quadratic_params *p 
+    = (struct quadratic_params *) params;
+
+  double a = p->a;
+  double b = p->b;
+  double c = p->c;
+
+  return (a * x + b) * x + c;
+}
+
+double
+quadratic_deriv (double x, void *params)
+{
+  struct quadratic_params *p 
+    = (struct quadratic_params *) params;
+
+  double a = p->a;
+  double b = p->b;
+  double c = p->c;
+
+  return 2.0 * a * x + b;
+}
+
+void
+quadratic_fdf (double x, void *params, 
+               double *y, double *dy)
+{
+  struct quadratic_params *p 
+    = (struct quadratic_params *) params;
+
+  double a = p->a;
+  double b = p->b;
+  double c = p->c;
+
+  *y = (a * x + b) * x + c;
+  *dy = 2.0 * a * x + b;
+}