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[/] [openrisc/] [trunk/] [gnu-old/] [newlib-1.17.0/] [newlib/] [libm/] [common/] [s_matherr.c] - Rev 158
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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; }
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