Sadly, Solaris doesn't implement _controlFP()

In that case, maybe something like this would work for you? 

sub rnd{ 
    my( $p, $n ) = @_; 
    return sprintf "%.${p}f", $n + "0.5e-$p" 
};;

print $_, ': ', rnd( 5, $_ ) for 
    0.000005, 0.000015, 0.000025, 0.000035, 0.000045, 
    0.000055, 0.000065, 0.000075, 0.000085, 0.000095;;

5e-006 :  0.00001
1.5e-005 :  0.00002
2.5e-005 :  0.00003
3.5e-005 :  0.00004
4.5e-005 :  0.00005
5.5e-005 :  0.00006
6.5e-005 :  0.00007
7.5e-005 :  0.00008
8.5e-005 :  0.00009
9.5e-005 :  0.00010

[download]

Even if it isn't faster than your code -- which instinct tells me it should be -- then it is at least a darn sight clearer :)

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Re^9: RFC: Large Floating Point Numbers - Rounding Errors by BrowserUk
in thread RFC: Large Floating Point Numbers - Rounding Errors by GAVollink

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