Faster Aproximate Square Root?

[Insider1984]

Is there a semi accurate method of calculating the approximate square root of a number?

We are using a distance formula on some shorts and would like to approximate the square root to save time.


Any ideas?

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Insider
4 year 'on the fly' programmer
C, C++, C#, MFC, Basic, Java ASP.NET

 

[earthandfire]

These may be of some help:

http://michael.dipperstein.com/sqrt/sqrt.html

 

[Guru7777]

Am I missing the point? Why don't you use Math.Sqrt() to find the square root? It is late, so forgive me if I'm being daft.

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[Insider1984]

Guru7777, the sqrt function provided is far to acurrate and too slow for our needs. If we can bit shift

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Insider
4 year 'on the fly' programmer
C, C++, C#, MFC, Basic, Java ASP.NET

 

[JohnYingling]

Hmmm.

For Shorts, I would be tempted to use a Static array of 32768, including 0, and fill it up on start-up.

http://www.moldyoldy.com/VBComparedemo

- free online Compare/Diff of snippets

 

[dEVooXiAm]

As far as square root is a floating point number, there can't be any bit shifts.
So you either use the link earthandfire suggested, or use LookUp table as JohnYingling suggested. You probably won't get a faster method then using LookUp table, but it's memory consuming so you have to consider this too.

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