69 lines
1.2 KiB
C
69 lines
1.2 KiB
C
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/* @(#)z_log10.c 1.0 98/08/13 */
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/******************************************************************
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* Logarithm
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*
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* Input:
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* x - floating point value
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*
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* Output:
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* logarithm of x
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*
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* Description:
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* This routine returns the logarithm of x (base 10).
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*
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*****************************************************************/
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/*
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FUNCTION
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<<log10>>, <<log10f>>---base 10 logarithms
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INDEX
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log10
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INDEX
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log10f
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ANSI_SYNOPSIS
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#include <math.h>
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double log10(double <[x]>);
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float log10f(float <[x]>);
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TRAD_SYNOPSIS
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#include <math.h>
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double log10(<[x]>)
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double <[x]>;
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float log10f(<[x]>)
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float <[x]>;
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DESCRIPTION
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<<log10>> returns the base 10 logarithm of <[x]>.
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It is implemented as <<log(<[x]>) / log(10)>>.
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<<log10f>> is identical, save that it takes and returns <<float>> values.
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RETURNS
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<<log10>> and <<log10f>> return the calculated value.
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See the description of <<log>> for information on errors.
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PORTABILITY
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<<log10>> is ANSI C. <<log10f>> is an extension.
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*/
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#include "fdlibm.h"
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#include "zmath.h"
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#ifndef _DOUBLE_IS_32BITS
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double
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_DEFUN (log10, (double),
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double x)
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{
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return (logarithm (x, 1));
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}
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#endif /* _DOUBLE_IS_32BITS */
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