ADDED   mttroot/mtt/lib/cr/perl/lcos.pm
Index: mttroot/mtt/lib/cr/perl/lcos.pm
==================================================================
--- mttroot/mtt/lib/cr/perl/lcos.pm
+++ mttroot/mtt/lib/cr/perl/lcos.pm
@@ -0,0 +1,120 @@
+#-------------------------------------------------------------------------------
+#			Model Transformation Tools
+#-------------------------------------------------------------------------------
+
+
+package lcos;
+
+#-------------------------------------------------------------------------------
+#		linear constitutive relationship with cosine modulation
+#-------------------------------------------------------------------------------
+
+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(&lcos);	# CR name
+    %EXPORT_TAGS = ( );
+}
+
+#-------------------------------------------------------------------------------
+# declaration of specific component implementations
+#-------------------------------------------------------------------------------
+sub lcos_emtf(@);		# EMTF
+
+#-------------------------------------------------------------------------------
+# main function: selects which subfunction to call
+#-------------------------------------------------------------------------------
+sub lcos (@) {
+
+    my $retval;
+
+    $_ = $_[0];
+
+    s/\((.*)\)/$1/;		# strip brackets
+    my @args = split (/,/);	# split arguments
+
+    $_ = $args[0];		# get component type
+
+    # select rule to use
+    if (/EMTF|emtf/)	{ $retval = lcos_emtf	(@args); }
+    
+    # if a substitution has been made ($retval)
+    if ($retval)
+    {
+	return $retval;		# return substituted expression
+    }
+    else			# return nothing
+    {
+	return;
+    }
+}
+
+#-------------------------------------------------------------------------------
+# EMTF
+#-------------------------------------------------------------------------------
+sub lcos_emtf (@) {
+
+    my @args = @_;
+    my $retval = '';
+
+    if ($#args == 11-1)
+    {
+	my ($component,
+	    $gain_causality,
+	    $gain,
+	    $out_causality,
+	    $out_port,
+	    $input,
+	    $in_causality,
+	    $in_port,
+	    $mod_input,
+	    $mod_causality,
+	    $mod_port) = @args;
+
+	if ((($mod_port == 3) and
+	     ($out_causality eq $in_causality))
+	    and
+	    ((($out_causality eq $gain_causality) and
+	      ($out_port == 2))
+	     or
+	     (($out_causality ne $gain_causality) and
+	      ($out_port == 1))))
+	{
+	    $retval = "(($input)*($gain)*(cos($mod_input)))";
+	}
+	elsif ((($mod_port == 3) and
+		($out_causality eq $in_causality))
+	       and
+	       ((($out_causality ne $gain_causality) and
+		 ($out_port == 2))
+		or
+		(($out_causality eq $gain_causality) and
+		 ($out_port == 1))))
+	{
+	    $retval = "(($input)/(($gain)*(cos($mod_input))))";
+	}
+    }
+    
+    if ($retval)
+    {
+	return $retval;
+    }
+    else
+    {
+	return;
+    }
+}
+
+#-------------------------------------------------------------------------------
+1;				# return true
+