Hello, whilst putting together a reporting page I found that some of my numbers were wrong - I was getting 99% even though it should have been 100%. Prodding around and writing some test scripts I found that it was related to floating point division and sprintf rounding down. This code demonstrates some oddness:

foreach my $int ( 1 .. 600 ) {
    my $number = $int / $int;
    next if $number == 1;
    warn "$int / $int != 1 (== $number)\n";
}

produces: 

49 / 49 != 1 (== 1)
98 / 98 != 1 (== 1)
103 / 103 != 1 (== 1)
107 / 107 != 1 (== 1)
161 / 161 != 1 (== 1)
187 / 187 != 1 (== 1)
196 / 196 != 1 (== 1)
197 / 197 != 1 (== 1)
206 / 206 != 1 (== 1)
214 / 214 != 1 (== 1)
237 / 237 != 1 (== 1)
...

[download]

Now I know that $num / $num != 1 sometimes because of floating point considerations - but I am keen to know more. For instance why is $number always displayed as '1'? Also why do the hits seem to happen more often as the numbers get larger ( twice for 1..100, eleven times for 401..500)?

In reply to Insights sought into floating point division strangeness by EvdB

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