Changeset 34083 for trunk/ppSim/src/ppSimInsertGalaxies.c

Timestamp:

Jun 26, 2012, 11:25:02 AM (14 years ago)

Author:

eugene

Message:

fix numerical round-off errors and aperture bias in ppSimInsertStars

File:

• trunk/ppSim/src/ppSimInsertGalaxies.c (modified) (2 diffs)

trunk/ppSim/src/ppSimInsertGalaxies.c

@@ -2 +2 @@
 static char *defaultModel = "PS_MODEL_SERSIC";
 
-float imageSum (psImage *image) {
-    float sum = 0.0;
+// this is used to measure the inserted flux as a difference of 2 large numbers : must use
+// 'double' or we get floating point errors and trends on a scale of ~0.005 mags at > -10 mags
+// instrumental
+double imageSum (psImage *image) {
+    double sum = 0.0;
     for (int iy = 0; iy < image->numRows; iy++) {
         for (int ix = 0; ix < image->numCols; ix++) {
@@ -165 +168 @@
         
         // insert the source flux in the image
-        float sum1 = imageSum(source->pixels);
+        double sum1 = imageSum(source->pixels);
         pmSourceAddWithOffset (source, PM_MODEL_OP_FULL, 0xff, dX, dY);
-        float sum2 = imageSum(source->pixels);
+        double sum2 = imageSum(source->pixels);
         float flux = sum2 - sum1;