33 lines
1.1 KiB
Perl
33 lines
1.1 KiB
Perl
sub euler_method {
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my ($t0, $t1, $k, $step_size) = @_;
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my @results = ( [0, $t0] );
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for (my $s = $step_size; $s <= 100; $s += $step_size) {
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$t0 -= ($t0 - $t1) * $k * $step_size;
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push @results, [$s, $t0];
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}
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return @results;
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}
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sub analytical {
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my ($t0, $t1, $k, $time) = @_;
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return ($t0 - $t1) * exp(-$time * $k) + $t1
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}
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my ($T0, $T1, $k) = (100, 20, .07);
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my @r2 = grep { $_->[0] % 10 == 0 } euler_method($T0, $T1, $k, 2);
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my @r5 = grep { $_->[0] % 10 == 0 } euler_method($T0, $T1, $k, 5);
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my @r10 = grep { $_->[0] % 10 == 0 } euler_method($T0, $T1, $k, 10);
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print "Time\t 2 err(%) 5 err(%) 10 err(%) Analytic\n", "-" x 76, "\n";
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for (0 .. $#r2) {
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my $an = analytical($T0, $T1, $k, $r2[$_][0]);
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printf "%4d\t".("%9.3f" x 7)."\n",
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$r2 [$_][0],
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$r2 [$_][1], ($r2 [$_][1] / $an) * 100 - 100,
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$r5 [$_][1], ($r5 [$_][1] / $an) * 100 - 100,
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$r10[$_][1], ($r10[$_][1] / $an) * 100 - 100,
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$an;
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}
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