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18b4e0e518
The comparison c == FP_INFINITE causes the function to return +inf as it expects x = +inf to always be larger than y. This shortcut causes several issues as it also returns +inf for the following cases: - fdim(+inf, +inf), expected (as per C99): +0.0 - fdim(-inf, any non NaN), expected: +0.0 I don't see a reason to keep the comparison as all the infinity cases return the correct result using just the ternary operation.
59 lines
1.1 KiB
C
59 lines
1.1 KiB
C
/* Copyright (C) 2002 by Red Hat, Incorporated. All rights reserved.
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*
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* Permission to use, copy, modify, and distribute this software
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* is freely granted, provided that this notice is preserved.
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*/
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/*
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FUNCTION
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<<fdim>>, <<fdimf>>---positive difference
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INDEX
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fdim
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INDEX
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fdimf
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SYNOPSIS
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#include <math.h>
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double fdim(double <[x]>, double <[y]>);
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float fdimf(float <[x]>, float <[y]>);
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DESCRIPTION
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The <<fdim>> functions determine the positive difference between their
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arguments, returning:
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. <[x]> - <[y]> if <[x]> > <[y]>, or
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@ifnottex
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. +0 if <[x]> <= <[y]>, or
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@end ifnottex
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@tex
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. +0 if <[x]> $\leq$ <[y]>, or
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@end tex
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. NAN if either argument is NAN.
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A range error may occur.
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RETURNS
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The <<fdim>> functions return the positive difference value.
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PORTABILITY
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ANSI C, POSIX.
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*/
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#include "fdlibm.h"
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#ifndef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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double fdim(double x, double y)
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#else
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double fdim(x,y)
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double x;
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double y;
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#endif
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{
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if (__fpclassifyd(x) == FP_NAN) return(x);
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if (__fpclassifyd(y) == FP_NAN) return(y);
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return x > y ? x - y : 0.0;
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}
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#endif /* _DOUBLE_IS_32BITS */
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