124 lines
3.0 KiB
C
124 lines
3.0 KiB
C
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/* @(#)s_matherr.c 5.1 93/09/24 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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FUNCTION
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<<matherr>>---modifiable math error handler
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INDEX
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matherr
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ANSI_SYNOPSIS
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#include <math.h>
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int matherr(struct exception *<[e]>);
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TRAD_SYNOPSIS
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#include <math.h>
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int matherr(*<[e]>)
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struct exception *<[e]>;
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DESCRIPTION
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<<matherr>> is called whenever a math library function generates an error.
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You can replace <<matherr>> by your own subroutine to customize
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error treatment. The customized <<matherr>> must return 0 if
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it fails to resolve the error, and non-zero if the error is resolved.
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When <<matherr>> returns a nonzero value, no error message is printed
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and the value of <<errno>> is not modified. You can accomplish either
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or both of these things in your own <<matherr>> using the information
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passed in the structure <<*<[e]>>>.
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This is the <<exception>> structure (defined in `<<math.h>>'):
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. struct exception {
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. int type;
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. char *name;
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. double arg1, arg2, retval;
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. int err;
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. };
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The members of the exception structure have the following meanings:
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o+
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o type
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The type of mathematical error that occured; macros encoding error
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types are also defined in `<<math.h>>'.
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o name
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a pointer to a null-terminated string holding the
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name of the math library function where the error occurred.
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o arg1, arg2
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The arguments which caused the error.
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o retval
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The error return value (what the calling function will return).
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o err
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If set to be non-zero, this is the new value assigned to <<errno>>.
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o-
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The error types defined in `<<math.h>>' represent possible mathematical
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errors as follows:
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o+
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o DOMAIN
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An argument was not in the domain of the function; e.g. <<log(-1.0)>>.
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o SING
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The requested calculation would result in a singularity; e.g. <<pow(0.0,-2.0)>>
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o OVERFLOW
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A calculation would produce a result too large to represent; e.g.
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<<exp(1000.0)>>.
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o UNDERFLOW
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A calculation would produce a result too small to represent; e.g.
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<<exp(-1000.0)>>.
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o TLOSS
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Total loss of precision. The result would have no significant digits;
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e.g. <<sin(10e70)>>.
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o PLOSS
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Partial loss of precision.
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o-
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RETURNS
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The library definition for <<matherr>> returns <<0>> in all cases.
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You can change the calling function's result from a customized <<matherr>>
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by modifying <<e->retval>>, which propagates backs to the caller.
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If <<matherr>> returns <<0>> (indicating that it was not able to resolve
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the error) the caller sets <<errno>> to an appropriate value, and prints
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an error message.
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PORTABILITY
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<<matherr>> is not ANSI C.
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*/
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#include "fdlibm.h"
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#ifdef __STDC__
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int matherr(struct exception *x)
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#else
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int matherr(x)
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struct exception *x;
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#endif
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{
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int n=0;
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if(x->arg1!=x->arg1) return 0;
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return n;
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}
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