Index: trunk/psphot/src/models/pmModel_PGAUSS.c
===================================================================
--- trunk/psphot/src/models/pmModel_PGAUSS.c	(revision 5593)
+++ trunk/psphot/src/models/pmModel_PGAUSS.c	(revision 8882)
@@ -16,20 +16,20 @@
     psF32 *PAR = params->data.F32;
 
-    psF32 X  = x->data.F32[0] - PAR[2];
-    psF32 Y  = x->data.F32[1] - PAR[3];
-    psF32 px = PAR[4]*X;
-    psF32 py = PAR[5]*Y;
-    psF32 z  = 0.5*PS_SQR(px) + 0.5*PS_SQR(py) + PAR[6]*X*Y;
+    psF32 X  = x->data.F32[0] - PAR[PM_PAR_XPOS];
+    psF32 Y  = x->data.F32[1] - PAR[PM_PAR_YPOS];
+    psF32 px = PAR[PM_PAR_SXX]*X;
+    psF32 py = PAR[PM_PAR_SYY]*Y;
+    psF32 z  = 0.5*PS_SQR(px) + 0.5*PS_SQR(py) + PAR[PM_PAR_SXY]*X*Y;
     psF32 t  = 1 + z + z*z/2.0;
     psF32 r  = 1.0 / (t + z*z*z/6.0); /* exp (-Z) */
-    psF32 f  = PAR[1]*r + PAR[0];
+    psF32 f  = PAR[PM_PAR_FLUX]*r + PAR[PM_PAR_SKY];
 
     if (deriv != NULL) {
-        // note difference from a pure gaussian: q = PAR[1]*r
-        psF32 q = PAR[1]*r*r*t;
+        // note difference from a pure gaussian: q = PAR[PM_PAR_FLUX]*r
+        psF32 q = PAR[PM_PAR_FLUX]*r*r*t;
         deriv->data.F32[0] = +1.0;
         deriv->data.F32[1] = +r;
-        deriv->data.F32[2] = q*(2.0*px*PAR[4] + PAR[6]*Y);
-        deriv->data.F32[3] = q*(2.0*py*PAR[5] + PAR[6]*X);
+        deriv->data.F32[2] = q*(2.0*px*PAR[PM_PAR_SXX] + PAR[PM_PAR_SXY]*Y);
+        deriv->data.F32[3] = q*(2.0*py*PAR[PM_PAR_SYY] + PAR[PM_PAR_SXY]*X);
         deriv->data.F32[4] = -2.0*q*px*X;
         deriv->data.F32[5] = -2.0*q*py*Y;
@@ -78,7 +78,7 @@
     psF32 *PAR = params->data.F32;
 
-    psF64 A1   = PS_SQR(PAR[4]);
-    psF64 A2   = PS_SQR(PAR[5]);
-    psF64 A3   = PS_SQR(PAR[6]);
+    psF64 A1   = PS_SQR(PAR[PM_PAR_SXX]);
+    psF64 A2   = PS_SQR(PAR[PM_PAR_SYY]);
+    psF64 A3   = PS_SQR(PAR[PM_PAR_SXY]);
     psF64 Area = 2.0 * M_PI / sqrt(A1*A2 - A3);
     // Area is equivalent to 2 pi sigma^2
@@ -92,5 +92,5 @@
     norm *= 0.01;
     
-    psF64 Flux = params->data.F32[1] * Area * norm;
+    psF64 Flux = params->data.F32[PM_PAR_FLUX] * Area * norm;
 
     return(Flux);
@@ -154,12 +154,12 @@
 
     dP = 0;
-    dP += PS_SQR(dPAR[4] / PAR[4]);
-    dP += PS_SQR(dPAR[5] / PAR[5]);
+    dP += PS_SQR(dPAR[PM_PAR_SXX] / PAR[PM_PAR_SXX]);
+    dP += PS_SQR(dPAR[PM_PAR_SYY] / PAR[PM_PAR_SYY]);
     dP = sqrt (dP);
 
     status = true;
     status &= (dP < 0.5);
-    status &= (PAR[1] > 0);
-    status &= ((dPAR[1]/PAR[1]) < 0.5);
+    status &= (PAR[PM_PAR_FLUX] > 0);
+    status &= ((dPAR[PM_PAR_FLUX]/PAR[PM_PAR_FLUX]) < 0.5);
 
     if (status) return true;