Index: trunk/psModules/src/objects/pmSourcePhotometry.c
===================================================================
--- trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 32998)
+++ trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 33963)
@@ -899,15 +899,28 @@
 }
 
-double pmSourceModelWeight(const pmSource *Mi, int term, const bool unweighted_sum, const float covarFactor, psImageMaskType maskVal)
+double pmSourceModelWeight(const pmSource *Mi, int term, const pmSourceFitVarMode fitVarMode, const float covarFactor, psImageMaskType maskVal)
 {
     PS_ASSERT_PTR_NON_NULL(Mi, NAN);
-    double flux = 0, wt = 0, factor = 0;
+    double flux = 0, wt = 1.0, factor = 0;
 
     const psImage *Pi = Mi->modelFlux;
     assert (Pi != NULL);
-    const psImage *Wi = Mi->variance;
-    if (!unweighted_sum) {
-        assert (Wi != NULL);
-    }
+
+    const psImage *Wi = NULL;
+    switch (fitVarMode) {
+      case PM_SOURCE_PHOTFIT_CONST:
+	break;
+      case PM_SOURCE_PHOTFIT_IMAGE_VAR:
+	Wi = Mi->variance;
+        psAssert (Wi, "programming error");
+	break;
+      case PM_SOURCE_PHOTFIT_MODEL_VAR:
+	Wi = Mi->modelVar;
+        psAssert (Wi, "programming error");
+	break;
+      case PM_SOURCE_PHOTFIT_NONE:
+	psAbort("programming error");
+    }	
+
     const psImage *Ti = Mi->maskObj;
     assert (Ti != NULL);
@@ -915,10 +928,8 @@
     for (int yi = 0; yi < Pi->numRows; yi++) {
         for (int xi = 0; xi < Pi->numCols; xi++) {
-            if (Ti->data.PS_TYPE_IMAGE_MASK_DATA[yi][xi] & maskVal)
-                continue;
-            if (!unweighted_sum) {
+            if (Ti->data.PS_TYPE_IMAGE_MASK_DATA[yi][xi] & maskVal) continue;
+            if (fitVarMode != PM_SOURCE_PHOTFIT_CONST) {
                 wt = covarFactor * Wi->data.F32[yi][xi];
-                if (wt == 0)
-                    continue;
+                if (wt == 0) continue;
             }
 
@@ -937,9 +948,6 @@
             }
 
-            if (unweighted_sum) {
-                flux += (factor * Pi->data.F32[yi][xi]);
-            } else {
-                flux += (factor * Pi->data.F32[yi][xi]) / wt;
-            }
+	    // wt is 1.0 for CONST
+	    flux += (factor * Pi->data.F32[yi][xi]) / wt;
         }
     }
@@ -947,5 +955,5 @@
 }
 
-double pmSourceModelDotModel (const pmSource *Mi, const pmSource *Mj, const bool unweighted_sum, const float covarFactor, psImageMaskType maskVal)
+double pmSourceModelDotModel (const pmSource *Mi, const pmSource *Mj, const pmSourceFitVarMode fitVarMode, const float covarFactor, psImageMaskType maskVal)
 {
     PS_ASSERT_PTR_NON_NULL(Mi, NAN);
@@ -955,5 +963,6 @@
     int xIs, xJs, yIs, yJs;
     int xIe, yIe;
-    double flux, wt;
+    double flux;
+    double wt = 1.0;
 
     const psImage *Pi = Mi->modelFlux;
@@ -962,8 +971,19 @@
     assert (Pj != NULL);
 
-    const psImage *Wi = Mi->variance;
-    if (!unweighted_sum) {
-        assert (Wi != NULL);
-    }
+    const psImage *Wi = NULL;
+    switch (fitVarMode) {
+      case PM_SOURCE_PHOTFIT_CONST:
+	break;
+      case PM_SOURCE_PHOTFIT_IMAGE_VAR:
+	Wi = Mi->variance;
+        psAssert (Wi, "programming error");
+	break;
+      case PM_SOURCE_PHOTFIT_MODEL_VAR:
+	Wi = Mi->modelVar;
+        psAssert (Wi, "programming error");
+	break;
+      case PM_SOURCE_PHOTFIT_NONE:
+	psAbort("programming error");
+    }	
 
     const psImage *Ti = Mi->maskObj;
@@ -995,13 +1015,20 @@
                 continue;
 
-            // XXX skip the nonsense weight pixels?
-            if (unweighted_sum) {
-                flux += (Pi->data.F32[yi][xi] * Pj->data.F32[yj][xj]);
-            } else {
+	    float value = (Pi->data.F32[yi][xi] * Pj->data.F32[yj][xj]);
+	    switch (fitVarMode) {
+	      case PM_SOURCE_PHOTFIT_CONST:
+		wt = 1.0;
+		break;
+	      case PM_SOURCE_PHOTFIT_IMAGE_VAR:
+	      case PM_SOURCE_PHOTFIT_MODEL_VAR:
                 wt = covarFactor * Wi->data.F32[yi][xi];
-                if (wt > 0) {
-                    flux += (Pi->data.F32[yi][xi] * Pj->data.F32[yj][xj]) / wt;
-                }
-            }
+		break;
+	      case PM_SOURCE_PHOTFIT_NONE:
+		psAbort("programming error");
+	    }
+            // skip pixels with nonsense weight values
+	    if (wt <= 0) continue;
+
+	    flux += value / wt;
         }
     }
@@ -1009,5 +1036,5 @@
 }
 
-double pmSourceDataDotModel (const pmSource *Mi, const pmSource *Mj, const bool unweighted_sum, const float covarFactor, psImageMaskType maskVal)
+double pmSourceDataDotModel (const pmSource *Mi, const pmSource *Mj, const pmSourceFitVarMode fitVarMode, const float covarFactor, psImageMaskType maskVal)
 {
     PS_ASSERT_PTR_NON_NULL(Mi, NAN);
@@ -1017,5 +1044,6 @@
     int xIs, xJs, yIs, yJs;
     int xIe, yIe;
-    double flux, wt;
+    double flux;
+    double wt = 1.0;
 
     const psImage *Pi = Mi->pixels;
@@ -1024,8 +1052,19 @@
     assert (Pj != NULL);
 
-    const psImage *Wi = Mi->variance;
-    if (!unweighted_sum) {
-        assert (Wi != NULL);
-    }
+    const psImage *Wi = NULL;
+    switch (fitVarMode) {
+      case PM_SOURCE_PHOTFIT_CONST:
+	break;
+      case PM_SOURCE_PHOTFIT_IMAGE_VAR:
+	Wi = Mi->variance;
+        psAssert (Wi, "programming error");
+	break;
+      case PM_SOURCE_PHOTFIT_MODEL_VAR:
+	Wi = Mi->modelVar;
+        psAssert (Wi, "programming error");
+	break;
+      case PM_SOURCE_PHOTFIT_NONE:
+	psAbort("programming error");
+    }	
 
     const psImage *Ti = Mi->maskObj;
@@ -1057,13 +1096,21 @@
                 continue;
 
-            // XXX skip the nonsense weight pixels?
-            if (unweighted_sum) {
-                flux += (Pi->data.F32[yi][xi] * Pj->data.F32[yj][xj]);
-            } else {
+	    float value = (Pi->data.F32[yi][xi] * Pj->data.F32[yj][xj]);
+	    switch (fitVarMode) {
+	      case PM_SOURCE_PHOTFIT_CONST:
+		wt = 1.0;
+		break;
+	      case PM_SOURCE_PHOTFIT_IMAGE_VAR:
+	      case PM_SOURCE_PHOTFIT_MODEL_VAR:
                 wt = covarFactor * Wi->data.F32[yi][xi];
-                if (wt > 0) {
-                    flux += (Pi->data.F32[yi][xi] * Pj->data.F32[yj][xj]) / wt;
-                }
-            }
+		break;
+	      case PM_SOURCE_PHOTFIT_NONE:
+		psAbort("programming error");
+	    }
+            // skip pixels with nonsense weight values
+	    if (wt <= 0) continue;
+
+	    flux += value / wt;
+
         }
     }