Re: numeric values acting funny

Your problem isn't in Perl, but in how numbers are represented.

There's an old rule in numerical analysis:

Never subtract very close values from each other

The problem, in very basic terms, is that your variables are the value you want, plus or minus some small "epsilon". If you subtract two very close values, all you end up with is ε₁ ± ε₂; in other words, garbage.

Your best bet is to restructure the formulas so the subtraction isn't necessary.

Do not rebuke them with harsh words ... but rather lead them gently - with URLs - so that they may learn wisdom.

Comment on Re: numeric values acting funny

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Re^2: numeric values acting funny by tachyon (Chancellor) on Dec 11, 2004 at 02:09 UTC
Your best bet is to restructure the formulas so the subtraction isn't necessary. This is I believe impossible given that the task rotates around money and spending some quantum of the available. Using integer math is probably a more practical solution. Math::Currency provides a nice transparent implementation that simulates dollars and cents, pounds and pence..... cheers tachyon	[reply]