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Asked: 2026-05-16T20:38:56+00:00

I am writing an iPhone app that needs to calculate the square root of

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I am writing an iPhone app that needs to calculate the square root of a number about 2000 times every 1/30th of a second. sqrt() works fine on a computer, but the frame rate drops to around 10 FPS on an iPhone or iPad, and I have already optimized the rest of the code. I have heard that this can be sped up dramatically by estimating the square root, but I can not find any code to do this. I only need one or two decimal places of precision. Any suggestions on how to do this, or other ways to speed things up would be appreciated.

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1 Answer

  1. Editorial Team

    How accurate do you want your estimate to be? If you know how close you want your estimate to be to the real sqrt the Newton’s Method is your friend.

    Do you know the range of values that are passed to sqrt? If so you can make up a look up table that is precomputed at startup (or even read from disk at startup depending on what turns out to be faster). Find the closest in the table to your input and you get your estimate.

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