Index: trunk/psphot/src/psphotApResid.c
===================================================================
--- trunk/psphot/src/psphotApResid.c	(revision 21183)
+++ trunk/psphot/src/psphotApResid.c	(revision 21359)
@@ -1,3 +1,5 @@
 # include "psphotInternal.h"
+
+bool psphotApResidMags_Unthreaded (int *nskip, int *nfail, psArray *sources, pmPSF *psf, pmSourcePhotometryMode photMode, psImageMaskType maskVal);
 
 # define SKIPSTAR(MSG) { psTrace ("psphot", 3, "invalid : %s", MSG); continue; }
@@ -29,5 +31,4 @@
 	nThreads = 0;
     }
-    // nThreads = 0; // XXX until testing is complete, do not thread this function
 
     bool measureAptrend = psMetadataLookupBool (&status, recipe, "MEASURE.APTREND");
@@ -94,43 +95,57 @@
 	for (int j = 0; j < cells->n; j++) {
 
-	    // allocate a job -- if threads are not defined, this just runs the job
-	    psThreadJob *job = psThreadJobAlloc ("PSPHOT_APRESID_MAGS");
-
-	    psArrayAdd(job->args, 1, cells->data[j]); // sources
-	    psArrayAdd(job->args, 1, psf);
-	    PS_ARRAY_ADD_SCALAR(job->args, photMode, PS_TYPE_S32);
-	    PS_ARRAY_ADD_SCALAR(job->args, maskVal,  PS_TYPE_IMAGE_MASK);
-
-	    PS_ARRAY_ADD_SCALAR(job->args, 0,        PS_TYPE_S32); // this is used as a return value for Nskip
-	    PS_ARRAY_ADD_SCALAR(job->args, 0,        PS_TYPE_S32); // this is used as a return value for Nfail
-
-	    if (!psThreadJobAddPending(job)) {
+	    if (nThreads) {
+		// allocate a job -- if threads are not defined, this just runs the job
+		psThreadJob *job = psThreadJobAlloc ("PSPHOT_APRESID_MAGS");
+
+		psArrayAdd(job->args, 1, cells->data[j]); // sources
+		psArrayAdd(job->args, 1, psf);
+		PS_ARRAY_ADD_SCALAR(job->args, photMode, PS_TYPE_S32);
+		PS_ARRAY_ADD_SCALAR(job->args, maskVal,  PS_TYPE_IMAGE_MASK);
+
+		PS_ARRAY_ADD_SCALAR(job->args, 0,        PS_TYPE_S32); // this is used as a return value for Nskip
+		PS_ARRAY_ADD_SCALAR(job->args, 0,        PS_TYPE_S32); // this is used as a return value for Nfail
+
+		if (!psThreadJobAddPending(job)) {
+		    psError(PS_ERR_UNKNOWN, false, "Unable to guess model.");
+		    psFree (job);
+		    return false;
+		}
+		psFree(job);
+	    } else {
+		int nskip = 0;
+		int nfail = 0;
+
+		if (!psphotApResidMags_Unthreaded (&nskip, &nfail, sources, psf, photMode, maskVal)) {
+		    psError(PS_ERR_UNKNOWN, false, "Unable to guess model.");
+		    return false;
+		}
+		Nskip += nskip;
+		Nfail += nfail;
+	    }		
+
+	}
+
+	if (nThreads) {
+	    // wait for the threads to finish and manage results
+	    if (!psThreadPoolWait (false)) {
 		psError(PS_ERR_UNKNOWN, false, "Unable to guess model.");
-		psFree (job);
 		return false;
 	    }
-	    psFree(job);
-
-	}
-
-	// wait for the threads to finish and manage results
-	if (!psThreadPoolWait (false)) {
-	    psError(PS_ERR_UNKNOWN, false, "Unable to guess model.");
-	    return false;
-	}
-
-	// we have only supplied one type of job, so we can assume the types here
-	psThreadJob *job = NULL;
-	while ((job = psThreadJobGetDone()) != NULL) {
-	    if (job->args->n < 1) {
-		fprintf (stderr, "error with job\n");
-	    } else {
-		psScalar *scalar = NULL;
-		scalar = job->args->data[4];
-		Nskip += scalar->data.S32;
-		scalar = job->args->data[5];
-		Nfail += scalar->data.S32;
+
+	    // we have only supplied one type of job, so we can assume the types here
+	    psThreadJob *job = NULL;
+	    while ((job = psThreadJobGetDone()) != NULL) {
+		if (job->args->n < 1) {
+		    fprintf (stderr, "error with job\n");
+		} else {
+		    psScalar *scalar = NULL;
+		    scalar = job->args->data[4];
+		    Nskip += scalar->data.S32;
+		    scalar = job->args->data[5];
+		    Nfail += scalar->data.S32;
+		}
+		psFree(job);
 	    }
-	    psFree(job);
 	}
     }
@@ -493,2 +508,36 @@
     return true;
 }
+
+bool psphotApResidMags_Unthreaded (int *nskip, int *nfail, psArray *sources, pmPSF *psf, pmSourcePhotometryMode photMode, psImageMaskType maskVal) {
+
+    int Nskip = 0;
+    int Nfail = 0;
+
+    for (int i = 0; i < sources->n; i++) {
+        pmSource *source = (pmSource *) sources->data[i];
+
+        if (source->type != PM_SOURCE_TYPE_STAR) SKIPSTAR ("NOT STAR");
+        if (source->mode &  PM_SOURCE_MODE_SATSTAR) SKIPSTAR ("SATSTAR");
+        if (source->mode &  PM_SOURCE_MODE_BLEND) SKIPSTAR ("BLEND");
+        if (source->mode &  PM_SOURCE_MODE_FAIL) SKIPSTAR ("FAIL STAR");
+        if (source->mode &  PM_SOURCE_MODE_POOR) SKIPSTAR ("POOR STAR");
+
+        if (!pmSourceMagnitudes (source, psf, photMode, maskVal)) {
+            Nskip ++;
+            psTrace ("psphot", 3, "skip : bad source mag");
+            continue;
+        }
+
+        if (!isfinite(source->apMag) || !isfinite(source->psfMag)) {
+            Nfail ++;
+            psTrace ("psphot", 3, "fail : nan mags : %f %f", source->apMag, source->psfMag);
+            continue;
+        }
+    }
+
+    // change the value of a scalar on the array (wrap this and put it in psArray.h)
+    *nskip = Nskip;
+    *nfail = Nfail;
+
+    return true;
+}