#+
# Name:
#    _CORRECT_NONLINEARITY_
#
# Purpose:
#    Corrects the raw data for detector non-linearity.
#
# Language:
#    Perl5
#
# Description:
#    This primitive corrects the raw data frame for non-linearity
#    applying a low-order polynomial fit from the
#    instrument web site   
#
# Notes:
#    -  This primitive is suitable for IRIS2
#    -  The linear counts (L) are given by the expression
#
#    L = M * (1.0 - 8.81352977E-12*M*M + 3.72642828E-16*M*M*M), 
#    For the IRIS2 original science grade device and
#    L = M * (1.0 + 8.555607E-12*M*M + 1.6591852E-16*M*M*M).
#    For the IRIS2 replacement (Mk2) science grade device and
#
#       where M is the measured ADU counts (valid for M=0-50000)
#  	  (http://www.aao.gov.au/iris2/iris2_linearity.html)
#
# Output Data:
#    -  Linearity-corrected frame inheriting the current frame's name
#    but with the _nl suffix.
#
# Tasks:
#    KAPPA: MATHS.
#
# Authors:
#    MJC: Malcolm J. Currie (JAC, Starlink)
#    CGT: Chris Tinney (AAO) - modified to use IRIS2 coefficients
#    CGT: Chris Tinney (AAO) - modified to do nothing on engineering data
#
# Copyright:
#    Copyright (C) 1998-2003 Particle Physics and Astronomy Research
#    Council.  All Rights Reserved.
#
#-

my $mode = $Frm->hdr( "METHOD" );
my $det  = $Frm->hdr( "DETECTOR" );
if ( $det =~ /Iris2.*Engineering/i || $det !~ /Iris2.*Science/i) {
   #
   # Issue a warning as we haven't worked out the correction yet.
   #
      orac_print "WARNING: DETECTOR=$det which is not yet implemented for linearity correction\n";
      orac_print "WARNING: No linearity correction performed.\n";

} else {
   if ( $mode =~ /IRIS_DRM/ ) {

   # Generate list of input and output filenames.
       my ( $in, $out ) = $Frm->inout( "_nl" );

   # Evaluate the expression that linearises the remianing data.
       orac_print "$det\n";
       if ( $det =~ /Iris2.*Mk2.*Science/i ) {
         orac_print "IRIS2 Mk2 correction : L=M*(1.0 + 8.555607E-12*M**2 + 1.6591852E-16*M**3).\n";
         $Mon{ "kappa_mon" }->obeyw( "maths", "out=$out ia=$in exp='IA*(1.0 + 8.555607E-12*IA*IA + 1.6591852E-16*IA*IA*IA)'" );
       } else {
         orac_print "IRIS2 Mk1 correction : L=M*(1.0 - 8.81352977E-12*M**2 + 3.72642828E-16*M**3).\n";
         $Mon{ "kappa_mon" }->obeyw( "maths", "out=$out ia=$in exp='IA*(1.0 - 8.81352977E-12*IA*IA + 3.72642828E-16*IA*IA*IA)'" );
       }
   # Report the processing status.
       orac_print "Frame $in linearity corrected to form $out.\n";

   # Now update the output filename in the Frame object.
       $Frm->file( $out );

   } else {
   #
   # Issue a warning if this is MRM data, but proceed on.
   #
      orac_print "WARNING: METHOD=$mode which is unusual for IRIS2 imaging data\n";
      orac_print "WARNING: No linearity correction of $mode data performed.\n";
   }
}
#orac_print "\n";

# Podule
# ======

=head1 NAME

_CORRECT_NONLINEARITY_PRE_POST_ -- Corrects the post-pre differenced raw data for detector non-linearity.

=head1 DESCRIPTION

This primitive corrects the raw data frame for non-linearity
applying a low-order polynomial fit for IRIS2. The correction 
is applied to the raw data.
(http://www.aao.gov.au/iris2/iris2_linearity.html)
 
=head1 NOTES

=over 4

=item *

This primitive is suitable for IRIS2.

=back

=head1 OUTPUT DATA

=over 4

=item *

Linearity-corrected frame inheriting the current frame's name
but with the _nl suffix.

=item *

Linear counts (L) are given by the expression
L = M * (1.0 - 8.81352977E-12*M*M + 3.72642828E-16*M*M*M), 
where M are the measured ADU counts (valid for M=0-50000)

=back

=head1 TASKS

KAPPA: MATHS.

=head1 AUTHORS

MJC: Malcolm J. Currie (JAC, Starlink)
CGT: Chris Tinney (AAO) - modified to use IRIS2 coefficients

=head1 COPYRIGHT

Copyright (C) 1998-2003 Particle Physics and Astronomy Research
Council.  All Rights Reserved.

=cut