Re: [perl #24092] sprintf problem

Nick Ing-Simmons wrote:
> But:
> 
> perl -e "print sprintf('%.20f', '1.045')"
> 1.04499999999999992895
> 
> The boundary is drawn an 5 in next digit down so that falls under it.
> 

I don't know if you should necessarily draw that conclusion.  There no generic 
way to know when the actual binary representation is inexact (like it is in this 
case).  In any case, your code is subtly different, since you are passing a 
string, which Perl then converts to a number.  There is frequently a difference 
between an asserted and a calculated floating point number.

The moral of the story is when using floating point numbers and requiring 
significant accuracy, Math:::BigFloat is a much better choice than any general 
floating point library.

John

-- 
John Peacock
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Rowman & Littlefield Publishing Group
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• [perl #24092] sprintf problem by Alex
• Re: [perl #24092] sprintf problem by Nick Ing-Simmons
• Re: [perl #24092] sprintf problem by John Peacock
• Re: [perl #24092] sprintf problem by John Peacock