modulo of doubles in objective-c

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How to make a modulo operation in objective-c / cocoa touch?

Can somebody explain to me why here the value of "myModValue" is 1.73472e-18 but when x would be 0.1 or 0.4 it's correctly 0? Is there a better way to get the modulo-value of two doubles?

double x = 0.3;
double y = 0.1;
double myModValue = fmod(x, y);

Thanks Michael

EDIT: Tried the above code hardcoded (so not with the values of my project-variables) and the result is 0.1 I don't know why...

@Monolo No there's only explained how to do modulo operations with double values. So fmod() is the right function I think, but I'm getting this unexplainable result ^^ — Michael, Sep 08 '12 at 10:19

score 1 · Accepted Answer · edited May 23 '17 at 12:07

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Floating point numbers are not precisely accurate due to rounding errors, the value 1.73472e-18 is essentially 0 in floating point terms. This is why you shouldn't compare floats with ==.

See also this answer.

edited May 23 '17 at 12:07

Community

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answered Sep 08 '12 at 10:27

Vic Smith

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And harcoding the values means that the calculations are done by the compiler and rounded somehow - resulting in zero. – Sulthan Sep 08 '12 at 10:28

modulo of doubles in objective-c

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