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+#======================================================================
+#                    . / S V D F I T . P L 
+#                    doc: Sat Jul 31 22:09:25 1999
+#                    dlm: Sat Jul 31 22:45:40 1999
+#                    (c) 1999 A.M. Thurnherr
+#                    uE-Info: 61 36 NIL 0 0 72 2 2 4 ofnI
+#======================================================================
+
+# SVDFIT routine from Numerical Recipes adapted to ANTS
+
+# HISTORY:
+#	Jul 31, 1999: - manually converted from c-source
+
+# Notes:
+#   - x,y,sig are field numbers for data in $ants_
+#   - if sig is a negative number, -sig is used as constant input stddev
+#   - @a, @u, @v, @w, &funcs passed as refs
+#	- chi square is returned
+
+require "$ANTS/nrutil.pl";
+require "$ANTS/svbksb.pl";
+require "$ANTS/svdcmp.pl";
+
+{ # BEGIN static scope
+
+my($TOL) = 1.0e-5;
+
+sub svdfit($$$$$$$$)
+{
+	my($xfnr,$yfnr,$sig,$aR,$uR,$vR,$wR,$funcsR) = @_;
+	my($j,$i);										# int
+	my($chisq,$wmax,$tmp,$thresh,$sum);					# float
+	my(@b,@afunc);									# float[]
+
+	&vector(\@b,1,$#ants_);
+	&vector(\@afunc,1,$#{$aR});
+	for ($i=0; $i<=$#ants_; $i++) {
+		next if ($antsFlagged[$i]);
+		&$funcsR($ants_[$i][$xfnr],\@afunc);
+		$tmp = 1.0 / (($sig > 0) ? $ants_[$i][$sig] : -$sig);
+		for ($j=1; $j<=$#{$aR}; $j++) {
+			$uR->[$i][$j] = $afunc[$j]*$tmp;
+		}
+		$b[$i] = $ants_[$i][$yfnr]*$tmp;
+	}
+	&svdcmp($uR,$wR,$vR);
+	for ($j=1; $j<=$#{$aR}; $j++) {
+		$wmax = $wR->[$j] if ($wR->[$j] > $wmax);
+	}
+	$thresh = $TOL*$wmax;
+	for ($j=1; $j<=$#{$aR}; $j++) {
+		$wR->[$j] = 0 if ($wR->[$j] < $thresh);
+	}
+	&svbksb($uR,$wR,$vR,\@b,$aR);
+	for ($i=0; $i<=$#ants_; $i++) {
+		next if ($antsFlagged[$i]);
+		&$funcsR($ants_[$i][$xfnr],\@afunc);
+		for ($j=1; $j<=$#{$aR}; $j++) {
+			$sum += $aR->[$j]*$afunc[$j];
+		}
+		$tmp = ($ants_[$i][$yfnr] - $sum) /
+				(($sig > 0) ? $ants_[$i][$sig] : -$sig);
+		$chisq += $tmp * $tmp;
+	}
+	return $chisq;
+}
+
+} # END static scope