Index: trunk/psModules/src/imcombine/pmStack.c
===================================================================
--- trunk/psModules/src/imcombine/pmStack.c	(revision 18182)
+++ trunk/psModules/src/imcombine/pmStack.c	(revision 19207)
@@ -8,6 +8,6 @@
  *  @author GLG, MHPCC
  *
- *  @version $Revision: 1.32 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2008-06-19 01:59:59 $
+ *  @version $Revision: 1.33 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2008-08-26 02:06:44 $
  *  Copyright 2004-2007 Institute for Astronomy, University of Hawaii
  *
@@ -316,6 +316,6 @@
               // Use variance to check that the two are consistent
               float diff = pixelData->data.F32[0] - pixelData->data.F32[1];
-              float sigma = sqrtf(pixelVariances->data.F32[0] + pixelVariances->data.F32[1]);
-              if (fabs(diff) > rej * sigma) {
+              float sigma2 = pixelVariances->data.F32[0] + pixelVariances->data.F32[1];
+              if (PS_SQR(diff) > PS_SQR(rej) * sigma2) {
                   // Not consistent: mark both for inspection
                   combineInspect(inputs, x, y, pixelSources->data.U16[0]);