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/* @(#)s_matherr.c 5.1 93/09/24 */

/*

 * ====================================================

 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

 *

 * Developed at SunPro, a Sun Microsystems, Inc. business.

 * Permission to use, copy, modify, and distribute this

 * software is freely granted, provided that this notice

 * is preserved.

 * ====================================================

 */

/*

FUNCTION

        <<matherr>>---modifiable math error handler

INDEX

        matherr

ANSI_SYNOPSIS

        #include <math.h>

        int matherr(struct exception *<[e]>);

TRAD_SYNOPSIS

        #include <math.h>

        int matherr(*<[e]>)

        struct exception *<[e]>;

DESCRIPTION

<<matherr>> is called whenever a math library function generates an error.

You can replace <<matherr>> by your own subroutine to customize

error treatment.  The customized <<matherr>> must return 0 if

it fails to resolve the error, and non-zero if the error is resolved.

When <<matherr>> returns a nonzero value, no error message is printed

and the value of <<errno>> is not modified.  You can accomplish either

or both of these things in your own <<matherr>> using the information

passed in the structure <<*<[e]>>>.

This is the <<exception>> structure (defined in `<<math.h>>'):

.       struct exception {

.               int type;

.               char *name;

.               double arg1, arg2, retval;

.               int err;

.       };

The members of the exception structure have the following meanings:

o+

o type

The type of mathematical error that occured; macros encoding error

types are also defined in `<<math.h>>'.

o name

a pointer to a null-terminated string holding the

name of the math library function where the error occurred.

o arg1, arg2

The arguments which caused the error.

o retval

The error return value (what the calling function will return).

o err

If set to be non-zero, this is the new value assigned to <<errno>>.

o-

The error types defined in `<<math.h>>' represent possible mathematical

errors as follows:

o+

o DOMAIN

An argument was not in the domain of the function; e.g. <<log(-1.0)>>.

o SING

The requested calculation would result in a singularity; e.g. <<pow(0.0,-2.0)>>

o OVERFLOW

A calculation would produce a result too large to represent; e.g.

<<exp(1000.0)>>.

o UNDERFLOW

A calculation would produce a result too small to represent; e.g.

<<exp(-1000.0)>>.

o TLOSS

Total loss of precision.  The result would have no significant digits;

e.g. <<sin(10e70)>>.

o PLOSS

Partial loss of precision.

o-

RETURNS

The library definition for <<matherr>> returns <<0>> in all cases.

You can change the calling function's result from a customized <<matherr>>

by modifying <<e->retval>>, which propagates backs to the caller.

If <<matherr>> returns <<0>> (indicating that it was not able to resolve

the error) the caller sets <<errno>> to an appropriate value, and prints

an error message.

PORTABILITY

<<matherr>> is not ANSI C.

*/

#include "fdlibm.h"

#ifdef __STDC__

        int matherr(struct exception *x)

#else

        int matherr(x)

        struct exception *x;

#endif

{

        int n=0;

        if(x->arg1!=x->arg1) return 0;

        return n;

}