diff --git a/Math/vector.c b/Math/vector.c
new file mode 100644
index 00000000..ba2e3cfc
--- /dev/null
+++ b/Math/vector.c
@@ -0,0 +1,89 @@
+/**************************************************************************
+ * vector.c -- additional vector routines
+ *
+ * Written by Curtis Olson, started December 1997.
+ *
+ * Copyright (C) 1997  Curtis L. Olson  - curt@infoplane.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id$
+ * (Log is kept at end of this file)
+ **************************************************************************/
+
+
+#include <math.h>
+#include <stdio.h>
+
+#include "vector.h"
+
+#include "../Math/mat3.h"
+
+
+/* Map a vector onto the plane specified by normal */
+void map_vec_onto_cur_surface_plane(MAT3vec normal, MAT3vec v0, MAT3vec vec,
+				    MAT3vec result)
+{
+    MAT3vec u1, v, tmp;
+
+    /* calculate a vector "u1" representing the shortest distance from
+     * the plane specified by normal and v0 to a point specified by
+     * "vec".  "u1" represents both the direction and magnitude of
+     * this desired distance. */
+
+    /* u1 = ( (normal <dot> vec) / (normal <dot> normal) ) * normal */
+
+    MAT3_SCALE_VEC( u1,
+		    normal,
+		    ( MAT3_DOT_PRODUCT(normal, vec) /
+		      MAT3_DOT_PRODUCT(normal, normal)
+		      )
+		    );
+
+    /*
+    printf("  vec = %.2f, %.2f, %.2f\n", vec[0], vec[1], vec[2]);
+    printf("  v0 = %.2f, %.2f, %.2f\n", v0[0], v0[1], v0[2]);
+    printf("  u1 = %.2f, %.2f, %.2f\n", u1[0], u1[1], u1[2]);
+    */
+
+    /* calculate the vector "v" which is the vector "vec" mapped onto
+       the plane specified by "normal" and "v0". */
+
+    /* v = v0 + vec - u1 */
+
+    MAT3_ADD_VEC(tmp, v0, vec);
+    MAT3_SUB_VEC(v, tmp, u1);
+    /* printf("  v = %.2f, %.2f, %.2f\n", v[0], v[1], v[2]); */
+
+    /* Calculate the vector "result" which is "v" - "v0" which is a
+     * directional vector pointing from v0 towards v */
+
+    /* result = v - v0 */
+
+    MAT3_SUB_VEC(result, v, v0);
+    /* printf("  result = %.2f, %.2f, %.2f\n", 
+       result[0], result[1], result[2]); */
+}
+
+/* $Log$
+/* Revision 1.1  1997/12/22 04:13:17  curt
+/* Initial revision.
+/*
+ */
+
+
+
+
+
diff --git a/Math/vector.h b/Math/vector.h
new file mode 100644
index 00000000..c0f1be58
--- /dev/null
+++ b/Math/vector.h
@@ -0,0 +1,39 @@
+/**************************************************************************
+ * vector.h -- additional vector routines
+ *
+ * Written by Curtis Olson, started December 1997.
+ *
+ * Copyright (C) 1997  Curtis L. Olson  - curt@infoplane.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id$
+ * (Log is kept at end of this file)
+ **************************************************************************/
+
+
+#include "../Math/mat3.h"
+
+
+/* Map a vector onto the plane specified by normal */
+void map_vec_onto_cur_surface_plane(MAT3vec normal, MAT3vec v0, MAT3vec vec,
+				    MAT3vec result);
+
+
+/* $Log$
+/* Revision 1.1  1997/12/22 04:13:18  curt
+/* Initial revision.
+/*
+ */