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Integer exponentiation should avoid using floats #3163

Merged
merged 2 commits into from
Aug 18, 2016
Merged

Integer exponentiation should avoid using floats #3163

merged 2 commits into from
Aug 18, 2016
+14 −2

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endSly
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@endSly endSly commented Aug 16, 2016

Using float exponentiation generates error when working with long integers besides it's performance penalization.
Some examples:

61 ** 9 => 11694146092834141 # Expected 11694146092834140
126 ** 9 => 8004512848309156864 # Expected 8004512848309157376

Using Exponentiation by squaring it gives correct result.

@endSly endSly changed the title Integer exponentiation should avoid use float Integer exponentiation should avoid using floats Aug 16, 2016
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endSly commented Aug 16, 2016

It would be great to implement also Modular exponentiation

@ysbaddaden
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I understand this is accurate as well as faster now?

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endSly commented Aug 17, 2016

In my benchmarks I've not seen great differences in term of performance. It will be very dependent on the processor...

@asterite
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@endSly Thank you!!

@asterite asterite merged commit 2300f7c into crystal-lang:master Aug 18, 2016
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@endSly @ysbaddaden @asterite @jhass