File: Vector.pm

package info (click to toggle)
algotutor 0.8.6-3
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, sid
  • size: 580 kB
  • sloc: perl: 2,563; makefile: 41; php: 24; sh: 1
file content (159 lines) | stat: -rw-r--r-- 3,461 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
# Author:  Chao-Kuei Hung
# For more info, including license, please see doc/index.html

package Vector;
# Mathematical Vector

use strict;
use Carp;
use vars qw(@ISA);
@ISA = qw();

my (%generated);

BEGIN {

    my ($functemplate) = q{
	sub {
	    my ($self, $that) = @_;
	    my ($r) = bless [], ref($self);
	    my ($i);
	    if (ref $that) {
		croak "dimension mismatch (", $#$self+1, " vs ",
		    $#$that+1, ") in <OP>" unless $#$self == $#$that;
		for ($i=0; $i<=$#$self; ++$i) {
		    $r->[$i] = $self->[$i] <OP> $that->[$i];
		}
	    } else {
		for ($i=0; $i<=$#$self; ++$i) {
		    $r->[$i] = $self->[$i] <OP> $that;
		}
	    }
	    return $r;
	}
    };

    my (%functab) = (
	add => '+',
	sbt => '-',
	mul => '*',
	div => '/',
    );

    my ($name, $op);
    while (($name, $op) = each %functab) {
	my ($t) = $functemplate;
	$t =~ s/<OP>/$op/g;
	$generated{$name} = eval $t;
    }
}

# see perldoc overload, especially the "MAGIC AUTOGENERATION" section
use overload
    '='  => '_clone',
    '""' => 'stringify',
    '+'  => $generated{add},
    '-'  => $generated{sbt},
    'neg'=> 'negate',
    '*'  => $generated{mul},
    '/'  => $generated{div},
    'fallback' => undef
;

sub pw_mul { return $generated{mul}->(@_); }
sub pw_div { return $generated{div}->(@_); }

# Different from "Perl Cookbook", chap 13.6, p.461 "cloning objects"
# See Randal Schwartz's "Constructing Objects" at
# http://www.stonehenge.com/merlyn/UnixReview/col52.html
# (search for "three camps")
sub new {
    my ($proto, @data) = @_;
    my ($class) = ref $proto || $proto;
#    if (ref $data[0] eq "Vector") {
    if (ref $proto) {
	return bless [ @$proto ], $class;
    } else {
	return bless [@data], $class;
    }
}

# Copy constructor is very tricky. It is _not_ called until
# just before a mutator is applied to one of the reference
# variables sharing the same copy. See perldoc overload,
# especially the "Copy Constructor" section.
sub _clone {
    my ($a, $b, $switch) = @_;
    print STDERR "Vector::_clone : switch is undef!\n"
	unless defined $switch;
    # print STDERR $switch ? "+" : "-"; # always prints "-"
    return $switch ? bless([@$a],"Vector") : bless([@$b],"Vector");
}

sub stringify {
    my ($self) = @_;
    my ($r) = sprintf "[ %8g", $self->[0];
    foreach (@{$self}[1..$#$self]) {
	$r .= sprintf(", %8g", $_);
    }
    return $r . " ]";
}

sub negate {
    my ($self) = @_;
    return bless [map { -$_ } @$self], ref $self;
}

sub x { return $_[0]->[0]; }
sub y { return $_[0]->[1]; }
sub z { return $_[0]->[2]; }

sub dot {
# dot product
    my ($t) = $_[0]->pw_mul($_[1]);
    my ($s, $i);
    for ($i=0; $i<=$#$t; ++$i) {
	$s += $t->[$i];
    }
    return $s;
}

sub norm {
    my ($self) = @_;
    return sqrt($self->dot($self));
}

sub angle_cos {
    my ($self, $b) = @_;
    return $self->dot($b)/$self->norm()/$b->norm();
}

sub cob {
# change of basis
    my ($self, $b) = @_;
    die unless ($#$b == $#$self and $#$b == $#{$b->[0]});
    my ($r) = $self->new();
    map { $_ = 0; } @$r;
    my ($i);
    for ($i=0; $i<=$#$self; ++$i) {
	$r += $b->[$i]->pw_mul($self->[$i]);
    }
    return $r;
}

if ($0 =~ /Vector.pm$/) {
# being tested as a stand-alone program, so run test code.
    my ($p, $q, $r);
    $p = Vector->new(4,-3);
    $q = Vector->new(5,12);
    print $p+$q, ",", $p-$q, "\n";

    $r = $p;
    $r += $q;
    $q = $q->pw_div(2);
    print $p, ",", $q, ",", $r, ",", $p->pw_mul(3), ",", -$p, "\n";

}

1;