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computeRMS.pl
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Mon, Nov 25, 12:54

computeRMS.pl
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#!/usr/bin/perl
# Compute the RMS between 2 sets of multiple images
# from 2 files whose names are given in arguments
#
# file1 : list of predicted images with position relative in arcsec
# file2 : observed image with position relative in arcsec
#
# subroutine that converts an X and Y value read from DS9 according to
# a reference declaration
# Input @xc and @yc arrays are modified
sub convertXY
{
my $iref, $ra, $dec, $pixel, $pixelx, $pxc, $pyc;
($pxc, $pyc, $iref, $ra, $dec, $pixel, $pixelx) = @_;
# Convert the coordinates to relative coordinates
# if $iref == 0, nothing has to be done as it stays in WCS
if( $iref == 1 or $iref == 3 )
{
for( $i=0; $i<= $#$pxc; $i++)
{
@$pxc[$i] -= $ra + 360 if( abs(@$pxc[$i] - $ra) > 1 ); #correction if ra=0
@$pxc[$i] = (@$pxc[$i] - $ra)*$pixelx;
@$pyc[$i] = (@$pyc[$i] - $dec)*$pixel;
}
}
elsif( $iref == 2 )
{
for( $i=0; $i<= $#$pxc; $i++)
{
@$pxc[$i] -= $ra;
@$pyc[$i] -= $dec;
}
}
} # end of convertXY subroutine
# Read a list of images from DS9, save them in a file
# and modify the two pointers to the ra dec in relative arcsec arrays
# Return the name of the last image
sub readDS9
{
my $file;
( $file, $pra, $pdec ) = @_;
@ds9=`xpaget ds9 regions selected`;
open( OUT, ">$file");
foreach $line ( @ds9 )
{
if( $line =~ /ellipse\(([\d|\.]+),([\d|\.|\+|\-]+)/ )
{
chop;
@fld = split( '[{|}]',$line);
push @{$pra},$1;
push @{$pdec},$2;
print OUT "$1 $2\n";
}
}
close(OUT);
return $fld[1];
}
# Read a catalog of images and return 2 pointers of ra dec arrays
sub readFile
{
my $file;
($file,$pra,$pdec) = @_;
open(IN,$file);
while(<IN>)
{
chop;
@fld = split, ' ';
push @{$pra}, $fld[0];
push @{$pdec}, $fld[1];
}
close(IN);
}
#----------------------------------------------
# Main program
# ---------------------------------------------
#
# Private declaration to the main prog
my @ra1,@dec1,@ra2,@dec2;
$file1='s1.cat';
$file2='s2.cat';
# Read DS9, save into $file1 and exit
if( ! -e $file1 )
{
print "INFO: Save $file1\n";
readDS9($file1,\@ra1,\@dec1);
exit 0;
}
# Read the second set of images and convert to relative coords
$name=readDS9($file2,\@ra2,\@dec2);
@ref=(3,$ra2[0],$dec2[0],3600,-3600*cos($dec2[0]/180.*3.1415926));
convertXY(\@ra2,\@dec2,@ref);
# Retreive the first set of images and convert it
readFile($file1,\@ra1,\@dec1) || die "ERROR: $file1 not found\n";
convertXY(\@ra1,\@dec1,@ref);
# Compute the RMS
for( $i=0; $i <= $#ra1; $i++ )
{
$dx=$ra1[$i]-$ra2;
$dy=$dec1[$i]-$dec2;
$avg+=sqrt($dx*$dx+$dy*$dy);
$err+=$dx*$dx+$dy*$dy;
}
$avg/=$i;
$var=$err/$i - $avg*$avg;
$rms=sqrt($var);
# Print the distance and error bars
print "$name $avg +-$rms\n";
system("rm $file1 $file2");

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