Index: /trunk/psModules/src/camera/pmFPAfileIO.c
===================================================================
--- /trunk/psModules/src/camera/pmFPAfileIO.c	(revision 14937)
+++ /trunk/psModules/src/camera/pmFPAfileIO.c	(revision 14938)
@@ -27,4 +27,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/Makefile.am
===================================================================
--- /trunk/psModules/src/objects/Makefile.am	(revision 14937)
+++ /trunk/psModules/src/objects/Makefile.am	(revision 14938)
@@ -31,4 +31,5 @@
      pmPSF_IO.c \
      pmPSFtry.c \
+     pmTrend2D.c \
      pmGrowthCurve.c
 
@@ -60,4 +61,5 @@
      pmPSF_IO.h \
      pmPSFtry.h \
+     pmTrend2D.h \
      pmGrowthCurve.h
 
Index: /trunk/psModules/src/objects/pmGrowthCurve.c
===================================================================
--- /trunk/psModules/src/objects/pmGrowthCurve.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmGrowthCurve.c	(revision 14938)
@@ -5,6 +5,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.11 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.12 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:03:51 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -24,4 +24,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmModel.c
===================================================================
--- /trunk/psModules/src/objects/pmModel.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmModel.c	(revision 14938)
@@ -6,6 +6,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.14 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.15 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:04:07 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -25,4 +25,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmModelClass.c
===================================================================
--- /trunk/psModules/src/objects/pmModelClass.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmModelClass.c	(revision 14938)
@@ -6,6 +6,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.2 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.3 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -27,4 +27,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmModelUtils.c
===================================================================
--- /trunk/psModules/src/objects/pmModelUtils.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmModelUtils.c	(revision 14938)
@@ -5,6 +5,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.2 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.3 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:04:30 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -24,4 +24,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSource.c
===================================================================
--- /trunk/psModules/src/objects/pmSource.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSource.c	(revision 14938)
@@ -6,6 +6,6 @@
  *  @author EAM, IfA: significant modifications.
  *
- *  @version $Revision: 1.36 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-09-11 01:30:23 $
+ *  @version $Revision: 1.37 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -28,4 +28,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceContour.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceContour.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceContour.c	(revision 14938)
@@ -6,6 +6,6 @@
  *  @author EAM, IfA: significant modifications.
  *
- *  @version $Revision: 1.8 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.9 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -27,4 +27,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceFitModel.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceFitModel.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceFitModel.c	(revision 14938)
@@ -6,6 +6,6 @@
  *  @author GLG, MHPCC
  *
- *  @version $Revision: 1.25 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.26 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -27,4 +27,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceFitSet.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceFitSet.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceFitSet.c	(revision 14938)
@@ -6,6 +6,6 @@
  *  @author GLG, MHPCC
  *
- *  @version $Revision: 1.5 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-09-15 01:52:12 $
+ *  @version $Revision: 1.6 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -27,4 +27,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceIO.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceIO.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceIO.c	(revision 14938)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.46 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.47 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -34,4 +34,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceIO_CMP.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceIO_CMP.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceIO_CMP.c	(revision 14938)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.30 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.31 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -32,4 +32,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceIO_OBJ.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceIO_OBJ.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceIO_OBJ.c	(revision 14938)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.14 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.15 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -32,4 +32,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceIO_PS1_DEV_0.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceIO_PS1_DEV_0.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceIO_PS1_DEV_0.c	(revision 14938)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.12 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-09-15 00:58:34 $
+ *  @version $Revision: 1.13 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -32,4 +32,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceIO_RAW.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceIO_RAW.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceIO_RAW.c	(revision 14938)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.16 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.17 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -32,4 +32,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceIO_SMPDATA.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceIO_SMPDATA.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceIO_SMPDATA.c	(revision 14938)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.10 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.11 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -32,4 +32,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
@@ -184,6 +185,6 @@
 	pmSourceSetDophotType (source, dophot);
 
-	psF64 Area = 2.0 * M_PI * axes.major * axes.minor;
-	psF64 peakFlux = source->psfMag / Area;
+	double Area = 2.0 * M_PI * axes.major * axes.minor;
+	double peakFlux = source->psfMag / Area;
 
 	source->peak = pmPeakAlloc(PAR[PM_PAR_XPOS], PAR[PM_PAR_YPOS], peakFlux, PM_PEAK_LONE);
Index: /trunk/psModules/src/objects/pmSourceIO_SX.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceIO_SX.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceIO_SX.c	(revision 14938)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.12 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.13 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -32,4 +32,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourcePhotometry.c
===================================================================
--- /trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 14938)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA; GLG, MHPCC
  *
- *  @version $Revision: 1.29 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.30 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -26,4 +26,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
@@ -94,4 +95,5 @@
 
     // measure object model photometry
+    // XXX use the pmPSF.FluxScale to get this value
     status = pmSourcePhotometryModel (&source->psfMag, source->modelPSF);
     status = pmSourcePhotometryModel (&source->extMag, source->modelEXT);
@@ -99,5 +101,5 @@
     if ((mode & PM_SOURCE_PHOT_APCORR) && isPSF && psf) {
         // convert to the equivalent 2D model?
-        source->psfMag += psPolynomial4DEval (psf->ApTrend, x, y, 0.0, 0.0);
+        source->psfMag += pmTrend2DEval (psf->ApTrend, x, y);
     }
 
Index: /trunk/psModules/src/objects/pmSourcePlotApResid.c
===================================================================
--- /trunk/psModules/src/objects/pmSourcePlotApResid.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourcePlotApResid.c	(revision 14938)
@@ -4,6 +4,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.3 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.4 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *  Copyright 2006 IfA, University of Hawaii
  */
@@ -29,4 +29,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourcePlotMoments.c
===================================================================
--- /trunk/psModules/src/objects/pmSourcePlotMoments.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourcePlotMoments.c	(revision 14938)
@@ -5,6 +5,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.8 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.9 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2006 IfA, University of Hawaii
@@ -32,4 +32,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourcePlotPSFModel.c
===================================================================
--- /trunk/psModules/src/objects/pmSourcePlotPSFModel.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourcePlotPSFModel.c	(revision 14938)
@@ -5,6 +5,6 @@
  *  @author EAM, IfA
  *
- *  @version $Revision: 1.10 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.11 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2006 IfA, University of Hawaii
@@ -32,4 +32,5 @@
 #include "pmGrowthCurve.h"
 #include "pmResiduals.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceSky.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceSky.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceSky.c	(revision 14938)
@@ -6,6 +6,6 @@
  *  @author EAM, IfA: significant modifications.
  *
- *  @version $Revision: 1.14 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.15 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -28,4 +28,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmSourceUtils.c
===================================================================
--- /trunk/psModules/src/objects/pmSourceUtils.c	(revision 14937)
+++ /trunk/psModules/src/objects/pmSourceUtils.c	(revision 14938)
@@ -6,6 +6,6 @@
  *  @author EAM, IfA: significant modifications.
  *
- *  @version $Revision: 1.2 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-08-24 00:11:02 $
+ *  @version $Revision: 1.3 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:05 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -28,4 +28,5 @@
 #include "pmResiduals.h"
 #include "pmGrowthCurve.h"
+#include "pmTrend2D.h"
 #include "pmPSF.h"
 #include "pmModel.h"
Index: /trunk/psModules/src/objects/pmTrend2D.c
===================================================================
--- /trunk/psModules/src/objects/pmTrend2D.c	(revision 14938)
+++ /trunk/psModules/src/objects/pmTrend2D.c	(revision 14938)
@@ -0,0 +1,174 @@
+/** @file  pmTrend2D.c
+ *
+ *  @author EAM, IfA
+ *
+ *  @version $Revision: 1.2 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-09-21 00:09:18 $
+ *
+ *  Copyright 2004 Institute for Astronomy, University of Hawaii
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+# include <pslib.h>
+# include "pmTrend2D.h"
+
+static void pmTrend2DFree (pmTrend2D *trend) {
+
+    if (trend == NULL) 
+        return;
+
+    psFree (trend->stats);
+    psFree (trend->poly);
+    psFree (trend->map);
+    return;
+}
+
+pmTrend2D *pmTrend2DAlloc (pmTrend2DMode mode, psImage *image, int nXtrend, int nYtrend, psStats *stats)
+{
+    assert (image);
+    assert (stats);
+
+    pmTrend2D *trend = (pmTrend2D *) psAlloc(sizeof(pmTrend2D));
+    psMemSetDeallocator(trend, (psFreeFunc) pmTrend2DFree);
+
+    trend->map = NULL;
+    trend->poly = NULL;
+    trend->stats = psMemIncrRefCounter (stats);
+    trend->mode = mode;
+	
+    switch (mode) {
+      case PM_TREND_POLY_ORD:
+	trend->poly = psPolynomial2DAlloc (PS_POLYNOMIAL_ORD, nXtrend, nYtrend);
+	break;
+
+      case PM_TREND_POLY_CHEB:
+	trend->poly = psPolynomial2DAlloc (PS_POLYNOMIAL_CHEB, nXtrend, nYtrend);
+	break;
+
+      case PM_TREND_MAP: {
+	  // binning defines the map scale relationship
+	  psImageBinning *binning = psImageBinningAlloc();
+	  binning->nXruff = nXtrend;
+	  binning->nYruff = nYtrend;
+	  binning->nXfine = image->numCols;
+	  binning->nYfine = image->numRows;
+
+	  trend->map = psImageMapAlloc (image, binning, stats);
+	  psFree (binning);
+	  break;
+      }
+
+      default:
+	psAbort ("error");
+    }
+    return (trend);
+}
+
+pmTrend2D *pmTrend2DFieldAlloc (pmTrend2DMode mode, int nXfield, int nYfield, int nXtrend, int nYtrend, psStats *stats)
+{
+    pmTrend2D *trend = (pmTrend2D *) psAlloc(sizeof(pmTrend2D));
+    psMemSetDeallocator(trend, (psFreeFunc) pmTrend2DFree);
+
+    trend->map = NULL;
+    trend->poly = NULL;
+    trend->stats = psMemIncrRefCounter (stats);
+    trend->mode = mode;
+	
+    switch (mode) {
+      case PM_TREND_POLY_ORD:
+	trend->poly = psPolynomial2DAlloc (PS_POLYNOMIAL_ORD, nXtrend, nYtrend);
+	break;
+
+      case PM_TREND_POLY_CHEB:
+	trend->poly = psPolynomial2DAlloc (PS_POLYNOMIAL_CHEB, nXtrend, nYtrend);
+	break;
+
+      case PM_TREND_MAP: {
+	  // binning defines the map scale relationship
+	  psImageBinning *binning = psImageBinningAlloc();
+	  binning->nXfine = nXfield;
+	  binning->nYfine = nYfield;
+	  binning->nXruff = nXtrend;
+	  binning->nYruff = nYtrend;
+
+	  trend->map = psImageMapAlloc (NULL, binning, stats);
+	  psFree (binning);
+	  break;
+      }
+
+      default:
+	psAbort ("error");
+    }
+    return (trend);
+}
+
+bool pmTrend2DFit (pmTrend2D *trend, psVector *mask, psMaskType maskVal, psVector *x, psVector *y, psVector *f, psVector *df) {
+
+    bool status;
+
+    switch (trend->mode) {
+      case PM_TREND_POLY_ORD:
+      case PM_TREND_POLY_CHEB:
+        status = psVectorClipFitPolynomial2D (trend->poly, trend->stats, mask, maskVal, f, df, x, y);
+	// we can use the API here which adjusts the polynomial order based on the number
+	// of points in the image, and potentially based on the fractional range of the
+	// data?
+	break;
+
+      case PM_TREND_MAP:
+	// XXX supply fraction from trend elements
+	// XXX need to add the API which adjusts the scale
+	status = psImageMapClipFit (trend->map, trend->stats, mask, maskVal, x, y, f, df);
+	break;
+
+      default:
+	psAbort ("error");
+    }
+    return status;
+}
+
+double pmTrend2DEval (pmTrend2D *trend, float x, float y) {
+
+    double result;
+
+    if (!trend) return 0.0;
+
+    switch (trend->mode) {
+      case PM_TREND_POLY_ORD:
+      case PM_TREND_POLY_CHEB:
+	result = psPolynomial2DEval (trend->poly, x, y);
+	break;
+
+      case PM_TREND_MAP:
+	result = psImageMapEval (trend->map, x, y);
+	break;
+
+      default:
+	psAbort ("error");
+    }
+    return result;
+}
+
+psVector *pmTrend2DEvalVector (pmTrend2D *trend, psVector *x, psVector *y) {
+
+    psVector *result;
+
+    switch (trend->mode) {
+      case PM_TREND_POLY_ORD:
+      case PM_TREND_POLY_CHEB:
+	result = psPolynomial2DEvalVector (trend->poly, x, y);
+	break;
+
+      case PM_TREND_MAP:
+	result = psImageMapEvalVector (trend->map, x, y);
+	break;
+
+      default:
+	psAbort ("error");
+    }
+    return result;
+}
Index: /trunk/psModules/src/objects/pmTrend2D.h
===================================================================
--- /trunk/psModules/src/objects/pmTrend2D.h	(revision 14938)
+++ /trunk/psModules/src/objects/pmTrend2D.h	(revision 14938)
@@ -0,0 +1,44 @@
+/* @file  pmTrend2D.h
+ *
+ * functions to represent ways of modeling a 2D trend
+ *
+ * @author EAM, IfA
+ *
+ * @version $Revision: 1.2 $ $Name: not supported by cvs2svn $
+ * @date $Date: 2007-09-21 00:09:18 $
+ * Copyright 2004 Maui High Performance Computing Center, University of Hawaii
+ */
+
+# ifndef PM_TREND_2D_H
+# define PM_TREND_2d_H
+
+/// @addtogroup Objects Object Detection / Analysis Functions
+/// @{
+
+typedef enum {
+    PM_TREND_POLY_ORD,
+    PM_TREND_POLY_CHEB,
+    PM_TREND_MAP,
+} pmTrend2DMode;
+
+typedef struct {
+    psPolynomial2D *poly;
+    psImageMap *map;
+    psStats *stats;
+    pmTrend2DMode mode; // POLY_ORD, POLY_CHEB, MAP
+} pmTrend2D;
+
+// allocate a pmTrend2D structure tied to an image dimensions.  nXtrend,nYtrend is the order for the polynomials, max number of grid cells for
+// psImageMap
+pmTrend2D *pmTrend2DAlloc (pmTrend2DMode mode, psImage *image, int nXtrend, int nYtrend, psStats *stats);
+
+// allocate a pmTrend2D tied to an abstract field with size nXfield,nYfield 
+pmTrend2D *pmTrend2DFieldAlloc (pmTrend2DMode mode, int nXfield, int nYfield, int nXtrend, int nYtrend, psStats *stats);
+
+bool pmTrend2DFit (pmTrend2D *trend, psVector *mask, psMaskType maskVal, psVector *x, psVector *y, psVector *f, psVector *df);
+
+double pmTrend2DEval (pmTrend2D *trend, float x, float y);
+psVector *pmTrend2DEvalVector (pmTrend2D *trend, psVector *x, psVector *y);
+
+/// @}
+# endif