1 files changed, 50 insertions, 0 deletions
diff --git a/gsl-1.9/doc/examples/eigen.c b/gsl-1.9/doc/examples/eigen.c
new file mode 100644
index 0000000..a24c912
--- /dev/null
+++ b/gsl-1.9/doc/examples/eigen.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <gsl/gsl_math.h>
+#include <gsl/gsl_eigen.h>
+
+int
+main (void)
+{
+  double data[] = { 1.0  , 1/2.0, 1/3.0, 1/4.0,
+                    1/2.0, 1/3.0, 1/4.0, 1/5.0,
+                    1/3.0, 1/4.0, 1/5.0, 1/6.0,
+                    1/4.0, 1/5.0, 1/6.0, 1/7.0 };
+
+  gsl_matrix_view m 
+    = gsl_matrix_view_array (data, 4, 4);
+
+  gsl_vector *eval = gsl_vector_alloc (4);
+  gsl_matrix *evec = gsl_matrix_alloc (4, 4);
+
+  gsl_eigen_symmv_workspace * w = 
+    gsl_eigen_symmv_alloc (4);
+  
+  gsl_eigen_symmv (&m.matrix, eval, evec, w);
+
+  gsl_eigen_symmv_free (w);
+
+  gsl_eigen_symmv_sort (eval, evec, 
+                        GSL_EIGEN_SORT_ABS_ASC);
+  
+  {
+    int i;
+
+    for (i = 0; i < 4; i++)
+      {
+        double eval_i 
+           = gsl_vector_get (eval, i);
+        gsl_vector_view evec_i 
+           = gsl_matrix_column (evec, i);
+
+        printf ("eigenvalue = %g\n", eval_i);
+        printf ("eigenvector = \n");
+        gsl_vector_fprintf (stdout, 
+                            &evec_i.vector, "%g");
+      }
+  }
+
+  gsl_vector_free (eval);
+  gsl_matrix_free (evec);
+
+  return 0;
+}