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perl/Examples/Chap9/Constraint.pm

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+
+
+###
+### Constraint.pm
+###
+
+## Chapter 9 section 4.1.3
+
+package Constraint;
+use Equation;
+@Constraint::ISA = qw(Equation);
+sub qualify {
+  my ($self, $prefix) = @_;
+  my %result = ("" => $self->constant);
+  for my $var ($self->varlist) {
+    $result{"$prefix.$var"} = $self->coefficient($var);
+  }
+  $self->new(%result);
+}
+sub new_constant {
+  my ($base, $val) = @_;
+  my $class = ref $base || $base;
+  $class->new("" => $val);
+}
+sub add_constant {
+  my ($self, $v) = @_;
+  $self->add_equations($self->new_constant($v));
+}
+
+sub mul_constant {
+  my ($self, $v) = @_;
+  $self->scale_equation($v);
+}
+package Constraint_Set;
+@Constraint_Set::ISA = 'Equation::System';
+
+sub constraints {
+  my $self = shift;
+  $self->equations;
+}
+
+1;