diff --git a/src/sqr.h b/src/sqr.h
new file mode 100644
--- /dev/null
+++ b/src/sqr.h
@@ -0,0 +1,60 @@
+/*
+ *
+ *  $Id$
+ *
+ *  This file is part of the Virtual Leaf.
+ *
+ *  The Virtual Leaf 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 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  The Virtual Leaf 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 the Virtual Leaf.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  From "Numerical recipes in C"
+ *
+ *  Copyright 2010 Roeland Merks.
+ *
+ */
+
+#ifndef _SQR_H_
+#define _SQR_H_
+
+/* static float sqrarg;
+#define SQR(a) ((sqrarg=(a)) == 0.0 ? 0.0 : sqrarg*sqrarg)
+
+static double dsqrarg;
+#define DSQR(a) ((dsqrarg=(a)) == 0.0 ? 0.0 : dsqrarg*dsqrarg)
+*/
+
+
+// redefine these macros as inline functions, to prevent scary
+// behavior.  (According to compiler warnings, the above macros from
+// Numerical Recipes in C are officially undefined...)
+//
+// However, they seem to work, but it seems safer to redefine them.
+// Inline functions will behave like macros anyhow.
+inline double DSQR( double a ) {
+  
+  if (a == 0.0) {
+    return 0.0;
+  } else {
+    return a*a;
+  }
+
+}
+
+inline float SQR( float a ) {
+   if (a == 0.0) {
+    return 0.0;
+  } else {
+    return a*a;
+  }
+}
+#endif