19 lines
290 B
C
19 lines
290 B
C
/* Implementation of fast inverse square root.
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* See http://en.wikipedia.org/wiki/Fast_inverse_square_root
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*/
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float fisqrt(float n)
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{
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long i;
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float x2, y;
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x2 = n * 0.5f;
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y = n;
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i = *(long *)&y;
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i = 0x5f3759df - (i>>1);
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y = *(float *)&i;
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y = y * (1.5f - (x2*y*y));
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return y;
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}
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