1 files changed, 32 insertions, 0 deletions
diff --git a/gsl-1.9/doc/examples/diff.c b/gsl-1.9/doc/examples/diff.c
new file mode 100644
index 0000000..b32e193
--- /dev/null
+++ b/gsl-1.9/doc/examples/diff.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <gsl/gsl_math.h>
+#include <gsl/gsl_deriv.h>
+
+double f (double x, void * params)
+{
+  return pow (x, 1.5);
+}
+
+int
+main (void)
+{
+  gsl_function F;
+  double result, abserr;
+
+  F.function = &f;
+  F.params = 0;
+
+  printf ("f(x) = x^(3/2)\n");
+
+  gsl_deriv_central (&F, 2.0, 1e-8, &result, &abserr);
+  printf ("x = 2.0\n");
+  printf ("f'(x) = %.10f +/- %.10f\n", result, abserr);
+  printf ("exact = %.10f\n\n", 1.5 * sqrt(2.0));
+
+  gsl_deriv_forward (&F, 0.0, 1e-8, &result, &abserr);
+  printf ("x = 0.0\n");
+  printf ("f'(x) = %.10f +/- %.10f\n", result, abserr);
+  printf ("exact = %.10f\n", 0.0);
+
+  return 0;
+}