1#!./perl -w 2# Now they'll be wanting biff! and zap! tests too. 3 4BEGIN { 5 chdir 't' if -d 't'; 6 @INC = '../lib'; 7 require './test.pl'; 8} 9 10# This calcualtion ought to be within 0.001 of the right answer. 11my $bits_in_uv = int (0.001 + log (~0+1) / log 2); 12 13# 3**30 < 2**48, don't trust things outside that range on a Cray 14# Likewise other 3 should not overflow 48 bits if I did my sums right. 15my @pow = ([ 3, 30, 1e-14], 16 [ 4, 32, 0], 17 [ 5, 20, 1e-14], 18 [2.5, 10, 1e-14], 19 [ -2, 69, 0], 20 [ -3, 30, 1e-14], 21); 22my $tests; 23$tests += $_->[1] foreach @pow; 24 25plan tests => 13 + $bits_in_uv + $tests; 26 27# (-3)**3 gave 27 instead of -27 before change #20167. 28# Let's test the other similar edge cases, too. 29is((-3)**0, 1, "negative ** 0 = 1"); 30is((-3)**1, -3, "negative ** 1 = self"); 31is((-3)**2, 9, "negative ** 2 = positive"); 32is((-3)**3, -27, "(negative int) ** (odd power) is negative"); 33 34# Positives shouldn't be a problem 35is(3**0, 1, "positive ** 0 = 1"); 36is(3**1, 3, "positive ** 1 = self"); 37is(3**2, 9, "positive ** 2 = positive"); 38is(3**3, 27, "(positive int) ** (odd power) is positive"); 39 40# And test order of operations while we're at it 41is(-3**0, -1); 42is(-3**1, -3); 43is(-3**2, -9); 44is(-3**3, -27); 45 46 47# Ought to be 32, 64, 36 or something like that. 48 49my $remainder = $bits_in_uv & 3; 50 51cmp_ok ($remainder, '==', 0, 'Sanity check bits in UV calculation') 52 or printf "# ~0 is %d (0x%d) which gives $bits_in_uv bits\n", ~0, ~0; 53 54# These are a lot of brute force tests to see how accurate $m ** $n is. 55# Unfortunately rather a lot of perl programs expect 2 ** $n to be integer 56# perfect, forgetting that it's a call to floating point pow() which never 57# claims to deliver perfection. 58foreach my $n (0..$bits_in_uv - 1) { 59 my $pow = 2 ** $n; 60 my $int = 1 << $n; 61 cmp_ok ($pow, '==', $int, "2 ** $n vs 1 << $n"); 62} 63 64foreach my $pow (@pow) { 65 my ($base, $max, $range) = @$pow; 66 my $expect = 1; 67 foreach my $n (0..$max-1) { 68 my $got = $base ** $n; 69 within ($got, $expect, $range, "$base ** $n got[$got] expect[$expect]"); 70 $expect *= $base; 71 } 72} 73