Index: trunk/psphot/src/models/pmModel_QGAUSS.c
===================================================================
--- trunk/psphot/src/models/pmModel_QGAUSS.c	(revision 4977)
+++ trunk/psphot/src/models/pmModel_QGAUSS.c	(revision 5129)
@@ -15,4 +15,9 @@
 *****************************************************************************/
 
+/* XXX EAM : we need a way to have user-set values for fix parameters */
+# define QG_S1  2.5
+# define dQG_S1 1.5
+/* dQG_S1 is QG_S1 - 1.0 */
+
 psF32 pmModelFunc_QGAUSS(psVector *deriv,
 			 const psVector *params,
@@ -27,5 +32,5 @@
     psF32 z  = 0.5*PS_SQR(px) + 0.5*PS_SQR(py) + PAR[6]*X*Y;
 
-    psF32 r  = 1.0 / (1 + PAR[7]*z + pow(z, 2.25));
+    psF32 r  = 1.0 / (1 + PAR[7]*z + pow(z, QG_S1));
     psF32 f  = PAR[1]*r + PAR[0];
 
@@ -33,5 +38,5 @@
         // note difference from a pure gaussian: q = params->data.F32[1]*r
         psF32 t = PAR[1]*r*r;
-	psF32 q = t*(PAR[7] + 2.25*pow(z, 1.25));
+	psF32 q = t*(PAR[7] + QG_S1*pow(z, dQG_S1));
 
         deriv->data.F32[0] = +1.0;
@@ -115,5 +120,5 @@
     norm = 0.0;
     for (z = 0.005; z < 50; z += 0.01) {
-	f = 1.0 / (1 + PAR[7]*z + pow(z, 2.25));
+	f = 1.0 / (1 + PAR[7]*z + pow(z, QG_S1));
 	norm += f;
     }
@@ -143,5 +148,5 @@
     // we can do this much better with intelligent choices here
     for (z = 0.0; z < 20.0; z += dz) {
-	f = 1.0 / (1 + PAR[7]*z + pow(z, 2.25));
+	f = 1.0 / (1 + PAR[7]*z + pow(z, QG_S1));
 	if (f < limit) break;
     }