start drawing rotation orbits

main.h

@@ -1,6 +1,8 @@
 #ifndef TRIANGLE_GROUP_MAIN_H
 #define TRIANGLE_GROUP_MAIN_H
 
+#include <gsl/gsl_linalg.h>
+
 #include "triangle.h"
 #include "linalg.h"
 #include "initcairo.h"
@@ -84,4 +86,16 @@ int processEvent(GraphicsInfo *info, XEvent *ev);
 void computeRotationMatrix(DrawingContext *ctx, gsl_matrix *result, const char *type);
 void updateMatrices(DrawingContext *ctx);
 
+static vector_t vectorFromGsl(gsl_vector *v)
+{
+	vector_t result;
+	LOOP(i) result.x[i] = gsl_vector_get(v, i);
+	return result;
+}
+
+static void vectorToGsl(vector_t v, gsl_vector *out)
+{
+	LOOP(i) gsl_vector_set(out, i, v.x[i]);
+}
+
 #endif