#!perl
use strict;
use warnings;
use Math::Matrix;
use Test::More tests => 36;
################################################################
note('diff() on a 4-by-5 matrix');
{
    my $x = Math::Matrix -> new([[ 3, -1,  5,  2,  8 ],
                                 [ 4,  0,  2, -3,  1 ],
                                 [ 2,  6, -5,  1, -2 ],
                                 [ 0, -3,  4,  2,  3 ]]);
    my $y = $x -> diff();
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [[  1,  1, -3, -5, -7 ],
                        [ -2,  6, -7,  4, -3 ],
                        [ -2, -9,  9,  1,  5 ]], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3, -1,  5,  2,  8 ],
                        [ 4,  0,  2, -3,  1 ],
                        [ 2,  6, -5,  1, -2 ],
                        [ 0, -3,  4,  2,  3 ]], '$x is unmodified');
}
note('diff(1) on a 4-by-5 matrix');
{
    my $x = Math::Matrix -> new([[ 3, -1,  5,  2,  8 ],
                                 [ 4,  0,  2, -3,  1 ],
                                 [ 2,  6, -5,  1, -2 ],
                                 [ 0, -3,  4,  2,  3 ]]);
    my $y = $x -> diff(1);
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [[  1,  1, -3, -5, -7 ],
                        [ -2,  6, -7,  4, -3 ],
                        [ -2, -9,  9,  1,  5 ]], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3, -1,  5,  2,  8 ],
                        [ 4,  0,  2, -3,  1 ],
                        [ 2,  6, -5,  1, -2 ],
                        [ 0, -3,  4,  2,  3 ]], '$x is unmodified');
}
note('diff(2) on a 4-by-5 matrix');
{
    my $x = Math::Matrix -> new([[ 3, -1,  5,  2,  8 ],
                                 [ 4,  0,  2, -3,  1 ],
                                 [ 2,  6, -5,  1, -2 ],
                                 [ 0, -3,  4,  2,  3 ]]);
    my $y = $x -> diff(2);
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [[  -4,   6,  -3,   6 ],
                        [  -4,   2,  -5,   4 ],
                        [   4, -11,   6,  -3 ],
                        [  -3,   7,  -2,   1 ]], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3, -1,  5,  2,  8 ],
                        [ 4,  0,  2, -3,  1 ],
                        [ 2,  6, -5,  1, -2 ],
                        [ 0, -3,  4,  2,  3 ]], '$x is unmodified');
}
################################################################
note('diff() on a 4-by-1 matrix');
{
    my $x = Math::Matrix -> new([[ 3 ],
                                 [ 4 ],
                                 [ 2 ],
                                 [ 0 ]]);
    my $y = $x -> diff();
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [[  1 ],
                        [ -2 ],
                        [ -2 ]], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3 ],
                        [ 4 ],
                        [ 2 ],
                        [ 0 ]], '$x is unmodified');
}
note('diff(1) on a 4-by-1 matrix');
{
    my $x = Math::Matrix -> new([[ 3 ],
                                 [ 4 ],
                                 [ 2 ],
                                 [ 0 ]]);
    my $y = $x -> diff(1);
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [[  1 ],
                        [ -2 ],
                        [ -2 ]], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3 ],
                        [ 4 ],
                        [ 2 ],
                        [ 0 ]], '$x is unmodified');
}
note('diff(2) on a 4-by-1 matrix');
{
    my $x = Math::Matrix -> new([[ 3 ],
                                 [ 4 ],
                                 [ 2 ],
                                 [ 0 ]]);
    my $y = $x -> diff(2);
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3 ],
                        [ 4 ],
                        [ 2 ],
                        [ 0 ]], '$x is unmodified');
}
################################################################
note('diff() on a 1-by-5 matrix');
{
    my $x = Math::Matrix -> new([[ 3, -1,  5,  2,  8 ]]);
    my $y = $x -> diff();
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [[ -4,  6, -3,  6 ]], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3, -1,  5,  2,  8 ]], '$x is unmodified');
}
note('diff(1) on a 1-by-5 matrix');
{
    my $x = Math::Matrix -> new([[ 3, -1,  5,  2,  8 ]]);
    my $y = $x -> diff(1);
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3, -1,  5,  2,  8 ]], '$x is unmodified');
}
note('diff(2) on a 1-by-5 matrix');
{
    my $x = Math::Matrix -> new([[ 3, -1,  5,  2,  8 ]]);
    my $y = $x -> diff(2);
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [[ -4,  6, -3,  6 ]], '$y has the right values');
    # Verify that modifying $y does not modify $x.
    my ($nrowy, $ncoly) = $y -> size();
    for my $i (0 .. $nrowy - 1) {
        for my $j (0 .. $ncoly - 1) {
            $y -> [$i][$j] += 100;
        }
    }
    is_deeply([ @$x ], [[ 3, -1,  5,  2,  8 ]], '$x is unmodified');
}
################################################################
note('diff() on an empty matrix');
{
    my $x = Math::Matrix -> new([]);
    my $y = $x -> diff();
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [], '$y has the right values');
    is_deeply([ @$x ], [], '$x is unmodified');
}
note('diff(1) on an empty matrix');
{
    my $x = Math::Matrix -> new([]);
    my $y = $x -> diff(1);
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [], '$y has the right values');
    is_deeply([ @$x ], [], '$x is unmodified');
}
note('diff(2) on an empty matrix');
{
    my $x = Math::Matrix -> new([]);
    my $y = $x -> diff(2);
    is(ref($y), 'Math::Matrix', '$y is a Math::Matrix');
    is_deeply([ @$y ], [], '$y has the right values');
    is_deeply([ @$x ], [], '$x is unmodified');
}