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lib/Math/Zap/Triangle2.pm  view on Meta::CPAN

=head3 accuracy

Get/Set accuracy for comparisons

=cut


my $accuracy = 1e-10;

sub accuracy
 {return $accuracy unless scalar(@_);
  $accuracy = shift();
 }


=head3 narrow

Narrow (colinear) colinear?

=cut


sub narrow($$)
 {my $t = shift;  # Triangle
  my $a = 1e-2;   # Accuracy
  my $A = shift;  # Action 0: return indicator, 1: confess 
  my $b = vector($t->{b}{x}-$t->{a}{x}, $t->{b}{y}-$t->{a}{y}, 0);                                           
  my $c = vector($t->{c}{x}-$t->{a}{x}, $t->{c}{y}-$t->{a}{y}, 0);                                           
  my $n = ($b x $c)->length < $a;
  confess "Narrow triangle2" if $n and $A;
  $n;      
 }


=head3 check

Check its a triangle

=cut


sub check(@)
 {if (debug)
   {for my $t(@_)
     {confess "$t is not a triangle2" unless ref($t) eq __PACKAGE__;
     }
   }
  @_;
 }


=head3 is

Test its a triangle

=cut


sub is(@)
 {for my $t(@_)
   {return 0 unless ref($t) eq __PACKAGE__;
   }
  'triangle2';
 }


=head3 components

Components of a triangle

=cut


sub a($)   {check(@_) if debug; $_[0]->{a}}
sub b($)   {check(@_) if debug; $_[0]->{b}}
sub c($)   {check(@_) if debug; $_[0]->{c}}

sub ab($)  {check(@_) if debug; ($_[0]->{b}-$_[0]->{a})}
sub ac($)  {check(@_) if debug; ($_[0]->{c}-$_[0]->{a})}
sub ba($)  {check(@_) if debug; ($_[0]->{a}-$_[0]->{b})}
sub bc($)  {check(@_) if debug; ($_[0]->{c}-$_[0]->{b})}
sub ca($)  {check(@_) if debug; ($_[0]->{a}-$_[0]->{c})}
sub cb($)  {check(@_) if debug; ($_[0]->{b}-$_[0]->{c})}

sub abc($) {check(@_) if debug; ($_[0]->{a}, $_[0]->{b}, $_[0]->{c})}

sub lab($)  {check(@_) if debug; line2($_[0]->{b}, $_[0]->{a})}
sub lac($)  {check(@_) if debug; line2($_[0]->{c}, $_[0]->{a})}
sub lba($)  {check(@_) if debug; line2($_[0]->{a}, $_[0]->{b})}
sub lbc($)  {check(@_) if debug; line2($_[0]->{c}, $_[0]->{b})}
sub lca($)  {check(@_) if debug; line2($_[0]->{a}, $_[0]->{c})}
sub lcb($)  {check(@_) if debug; line2($_[0]->{b}, $_[0]->{c})}


=head3 clone

Create a triangle from another triangle 

=cut


sub clone($)
 {my ($t) = check(@_); # Triangle   
  bless {a=>$t->a, b=>$t->b, c=>$t->c};
 }


=head3 permute

Cyclically permute the points of a triangle

=cut


sub permute($)
 {my ($t) = check(@_); # Triangle   
  bless {a=>$t->b, b=>$t->c, c=>$t->a};
 }


=head3 center

Center 

=cut


sub center($)
 {my ($t) = check(@_); # Triangle   
  ($t->a + $t->b + $t->c) / 3;
 }


=head3 area

Area 

=cut


sub area($)
 {my ($t) = check(@_); # Triangle   
  sqrt((($t->ab*$t->ab) * ($t->ac*$t->ac)) - ($t->ab * $t->ac))/2;