Index: trunk/psLib/src/math/psSpline.c
===================================================================
--- trunk/psLib/src/math/psSpline.c	(revision 42336)
+++ trunk/psLib/src/math/psSpline.c	(revision 42823)
@@ -194,8 +194,8 @@
  *****************************************************************************/
 psSpline1D *psSpline1DFitVector(
-    const psVector* x,                  ///< Ordinates.
-    const psVector* y,                  ///< Coordinates.
-    psF32 dyLower,			///< 1st derivative at lower bound
-    psF32 dyUpper)			///< 1st derivative at upper bound
+    const psVector* x,	      ///< Ordinates.
+    const psVector* y,	      ///< Coordinates.
+    psF32 dyLower,	      ///< if not NAN, lower-bound 1st derivative is defined
+    psF32 dyUpper)	      ///< if not NAN, lower-bound 1st derivative is defined
 {
     psTrace("psLib.math", 3, "---- %s() begin ----\n", __func__);