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Also replace 'This file is a part of' by 'This file is part of' for consistency git-svn-id: svn+ssh://svn.code.sf.net/p/mingw-w64/code/trunk@5147 4407c894-4637-0410-b4f5-ada5f102cad1
34 lines
863 B
C
34 lines
863 B
C
/**
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* This file has no copyright assigned and is placed in the Public Domain.
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* This file is part of the mingw-w64 runtime package.
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* No warranty is given; refer to the file DISCLAIMER.PD within this package.
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*/
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#include <math.h>
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#include <errno.h>
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#include "fastmath.h"
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/* asinh(x) = copysign(log(fabs(x) + sqrt(x * x + 1.0)), x) */
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double asinh(double x)
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{
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double z;
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if (!isfinite (x))
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return x;
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z = fabs (x);
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/* Avoid setting FPU underflow exception flag in x * x. */
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#if 0
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if ( z < 0x1p-32)
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return x;
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#endif
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/* Use log1p to avoid cancellation with small x. Put
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x * x in denom, so overflow is harmless.
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asinh(x) = log1p (x + sqrt (x * x + 1.0) - 1.0)
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= log1p (x + x * x / (sqrt (x * x + 1.0) + 1.0)) */
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z = __fast_log1p (z + z * z / (__fast_sqrt (z * z + 1.0) + 1.0));
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return ( x > 0.0 ? z : -z);
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}
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