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Date: Mon, 4 Sep 2000 08:09:15 -0400 (EDT)
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Subject: bin/21024: pow() ERANGE bug
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>Number:         21024
>Category:       bin
>Synopsis:       pow() ERANGE bug
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Sep 04 05:10:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Randall Hopper
>Release:        FreeBSD 3.4-RELEASE i386
>Organization:
self
>Environment:

	Stock 3.4-RELEASE.

>Description:

According to the man page:

   The functions exp(), expm1(), pow() detect if the computed value will
   overflow, set the global variable errno to ERANGE, and ...

However, pow() does not set errno to ERANGE on overflow.


>How-To-Repeat:

Example:  The attached code generates:  Inf  0

The output should be:  Inf 34    (34 is ERANGE)

#include <math.h>
#include <stdio.h>
#include <errno.h>
#include <ieeefp.h>

main()
{
   fpsetmask(0);
   printf( "%g\n", pow(1e300,2) );
   pow(1e300,2);
   printf( "%d\n", errno );
}


>Fix:
	
	Please update the pow() function to set errno on overflow.  Might
also check other likely suspects such as exp() and expm1().  --Thanks.


>Release-Note:
>Audit-Trail:
>Unformatted:


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