ADDED   mttroot/mtt/lib/cr/perl/Poly.pm
Index: mttroot/mtt/lib/cr/perl/Poly.pm
==================================================================
--- /dev/null
+++ mttroot/mtt/lib/cr/perl/Poly.pm
@@ -0,0 +1,122 @@
+#-------------------------------------------------------------------------------
+#			Model Transformation Tools
+#-------------------------------------------------------------------------------
+
+
+package Poly;
+
+#-------------------------------------------------------------------------------
+#		Polytropic constitutive relationship 
+#-------------------------------------------------------------------------------
+
+use strict;
+use warnings;
+
+#-------------------------------------------------------------------------------
+# standard module header (see perlmod for explanation)
+#-------------------------------------------------------------------------------
+BEGIN {
+    use Exporter   ();
+    our ($VERSION, @ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS);
+
+    $VERSION     = 1.00;
+
+    @ISA         = qw(Exporter);
+    @EXPORT      = qw(&Poly);	# CR name
+    %EXPORT_TAGS = ( );
+}
+
+#-------------------------------------------------------------------------------
+# declaration of specific component implementations
+#-------------------------------------------------------------------------------
+sub Poly_any(@);		# any component
+
+#-------------------------------------------------------------------------------
+# main function: selects which subfunction to call
+#-------------------------------------------------------------------------------
+sub Poly (@) {
+
+    my $retval;
+
+    $_ = $_[0];
+
+    s/\((.*)\)/$1/;		# strip brackets
+    my @args = split (/,/);	# split arguments
+
+    $_ = $args[0];		# get component type
+
+    # select rule to use
+    $retval = Poly_any	(@args);
+    
+    # if a substitution has been made ($retval)
+    if ($retval)
+    {
+	return $retval;		# return substituted expression
+    }
+    else			# return nothing
+    {
+	return;
+    }
+}
+
+#-------------------------------------------------------------------------------
+# any component
+#-------------------------------------------------------------------------------
+sub Poly_any (@) {
+
+    my @args = @_;
+    my $retval = '';
+
+    if ($#args == 16-1)
+    {
+	my ($component,
+	    $alpha,
+	    $out_causality,
+	    $out_port,
+	    $P1,
+	    $in1_causality,
+	    $in1_port,
+	    $P2,
+	    $in2_causality,
+	    $in2_port,
+	    $T1,
+	    $in3_causality,
+	    $in3_port,
+	    $Nothing,
+	    $in4_causality,
+	    $in4_port) = @args;
+
+	if (($in1_port == 1) and
+	    ($in1_causality eq 'effort') and
+	    ($in2_port == 2) and
+	    ($in2_causality eq 'effort') and
+	    ($in3_port == 3) and
+	    ($in3_causality eq 'effort') and
+	    ($in4_port == 4) and
+	    ($in4_causality eq 'flow'))
+	{
+	    if ($out_port != 4)
+	    {
+		return "(0)";
+	    }
+	    elsif ($out_causality eq 'effort')
+	    {
+		# return temperature T2
+		$retval = "($T1)*pow((($P2)/($P1)),($alpha))";
+	    }
+	}
+    }
+    
+    if ($retval)
+    {
+	return $retval;
+    }
+    else
+    {
+	return;
+    }
+}
+
+#-------------------------------------------------------------------------------
+1;				# return true
+