1 files changed, 33 insertions, 0 deletions
diff --git a/python/GHquad.c b/python/GHquad.c
new file mode 100644
index 00000000..bb02e18c
--- /dev/null
+++ b/python/GHquad.c
@@ -0,0 +1,33 @@
+#include "stdlib.h"
+#include "math.h"
+#include "stdio.h"
+
+extern int dstev_(char* JOBZ, int* n, double* D, double* E, double* Z, int* ldz, double* WORK, int* INFO);
+
+void GHquad(int n, double* Z, double* w) {
+    // Setup for eigenvalue computations
+    char JOBZ   = 'V'; // Compute eigenvalues & vectors
+    int INFO;
+    int i;
+    // Initialize array for workspace
+    double * WORK   = malloc(sizeof(double)*(2*n-2));
+
+    // Initialize array for eigenvectors
+    double * V      = malloc(sizeof(double)*n*n);
+
+    for(i = 0; i<n-1; i++){
+      w[i] = sqrt((i+1.)/2);
+    }
+
+    // Run eigen decomposition
+    dstev_(&JOBZ, &n, Z, w, V, &n, WORK, &INFO);
+
+    for (i=0; i<n; i++) {
+        w[i] = V[i*n] * V[i*n];
+	Z[i] *= sqrt(2);
+    }
+
+    // Deallocate temporary arrays
+    free(WORK);
+    free(V);
+}