Nice try. But...

No. It isn't.

YOU are wrong! Wrong! Wrong!

It is just a consequence of switching between base 10 and 2: 

#!/usr/bin/perl -wl
use strict;

for my $n (
    0.000005,
    0.000015,
    0.000025,
    0.000035,
    0.000045,
    0.000055,
    0.000065,
    0.000075,
    0.000085,
    0.000095,
) {
    printf "%.23f\n", $n;
}
__END__
0.00000500000000000000041
0.00001500000000000000038
0.00002500000000000000120
0.00003499999999999999693
0.00004500000000000000283
0.00005500000000000000196
0.00006499999999999999431
0.00007499999999999999343
0.00008500000000000000611
0.00009500000000000000523

[download]

Your assumption that 0.000035 is exactly the same as 0.000005 + 3*0.000010 was not correct.

Update: Please show the results for explicitly enumerated values and show more precision on the first value. Or I'll to do that myself a bit later when I will probably again have convenient access to a system with Inline::C installed on it and with _controlfp().

- tye        

In reply to Re^2: RFC: Large Floating Point Numbers - Rounding Errors (not Rounding mode) by tye
in thread RFC: Large Floating Point Numbers - Rounding Errors by GAVollink

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