* [Bug 60749] New: Do not need to link against -lm for fabs*()
@ 2013-08-15 20:36 bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
[not found] ` <bug-60749-11311-3bo0kxnWaOQUvHkbgXJLS5sdmw4N0Rt+2LY78lusg7I@public.gmane.org/>
0 siblings, 1 reply; 6+ messages in thread
From: bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r @ 2013-08-15 20:36 UTC (permalink / raw)
To: linux-man-u79uwXL29TY76Z2rM5mHXA
https://bugzilla.kernel.org/show_bug.cgi?id=60749
Bug ID: 60749
Summary: Do not need to link against -lm for fabs*()
Product: Documentation
Version: unspecified
Hardware: All
OS: Linux
Status: NEW
Severity: low
Priority: P1
Component: man-pages
Assignee: documentation_man-pages-ztI5WcYan/vQLgFONoPN62D2FQJk+8+b@public.gmane.org
Reporter: orion-CVdf0l11yl+B+jHODAdFcQ@public.gmane.org
Regression: No
>From the fabs(3) man page:
SYNOPSIS
#include <math.h>
double fabs(double x);
float fabsf(float x);
long double fabsl(long double x);
Link with -lm.
At least on RHEL5+ one does not appear to need to link with -lm.
# cat fabs.c
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
int main(int argc, char **argv)
{
printf("%f\n",fabs(atof(argv[1])));
printf("%f\n",fabsf((float)atof(argv[1])));
printf("%Lf\n",fabsl((long double)atof(argv[1])));
return 0;
}
# gcc -g -Wall fabs.c
# ./a.out -2.5
2.500000
2.500000
2.500000
# gcc -v
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-libgcj-multifile
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk
--disable-dssi --disable-plugin
--with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic
--host=x86_64-redhat-linux
Thread model: posix
gcc version 4.1.2 20080704 (Red Hat 4.1.2-54)
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug 60749] Do not need to link against -lm for fabs*()
[not found] ` <bug-60749-11311-3bo0kxnWaOQUvHkbgXJLS5sdmw4N0Rt+2LY78lusg7I@public.gmane.org/>
@ 2013-08-29 10:09 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2013-08-29 10:10 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r @ 2013-08-29 10:09 UTC (permalink / raw)
To: linux-man-u79uwXL29TY76Z2rM5mHXA
https://bugzilla.kernel.org/show_bug.cgi?id=60749
--- Comment #1 from Jeyaram <rjayavrp2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> ---
Following code also works fine without linking with -lm
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
int main(int argc, char **argv)
{
printf("%lf\n", pow(5,3));
return 0;
}
Actually, libc some how includes the math library
"/lib/i386-linux-gnu/libm.so.6".
If this file is not available, then following error message is displayed.
/usr/lib/gcc/i686-linux-gnu/4.7/cc1: error while loading shared libraries:
libm.so.6: cannot open shared object file: No such file or directory
I tried it by renaming libm.so.6.
Solution:
I request not to remove the line "Link with -lm". This is mandatory.
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug 60749] Do not need to link against -lm for fabs*()
[not found] ` <bug-60749-11311-3bo0kxnWaOQUvHkbgXJLS5sdmw4N0Rt+2LY78lusg7I@public.gmane.org/>
2013-08-29 10:09 ` [Bug 60749] " bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
@ 2013-08-29 10:10 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2013-11-13 16:08 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r @ 2013-08-29 10:10 UTC (permalink / raw)
To: linux-man-u79uwXL29TY76Z2rM5mHXA
https://bugzilla.kernel.org/show_bug.cgi?id=60749
--- Comment #2 from Jeyaram <rjayavrp2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> ---
Forgot to mention:
uname -a
Linux jeyaram-VirtualBox 3.8.0-25-generic #37-Ubuntu SMP Thu Jun 6 20:47:30 UTC
2013 i686 i686 i686 GNU/Linux
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug 60749] Do not need to link against -lm for fabs*()
[not found] ` <bug-60749-11311-3bo0kxnWaOQUvHkbgXJLS5sdmw4N0Rt+2LY78lusg7I@public.gmane.org/>
2013-08-29 10:09 ` [Bug 60749] " bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2013-08-29 10:10 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
@ 2013-11-13 16:08 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2013-11-13 16:08 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2014-03-10 13:26 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
4 siblings, 0 replies; 6+ messages in thread
From: bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r @ 2013-11-13 16:08 UTC (permalink / raw)
To: linux-man-u79uwXL29TY76Z2rM5mHXA
https://bugzilla.kernel.org/show_bug.cgi?id=60749
Alan <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org
Resolution|--- |INVALID
--- Comment #3 from Alan <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org> ---
Use of -lm is correct even if it happens not to be needed
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug 60749] Do not need to link against -lm for fabs*()
[not found] ` <bug-60749-11311-3bo0kxnWaOQUvHkbgXJLS5sdmw4N0Rt+2LY78lusg7I@public.gmane.org/>
` (2 preceding siblings ...)
2013-11-13 16:08 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
@ 2013-11-13 16:08 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2014-03-10 13:26 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
4 siblings, 0 replies; 6+ messages in thread
From: bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r @ 2013-11-13 16:08 UTC (permalink / raw)
To: linux-man-u79uwXL29TY76Z2rM5mHXA
https://bugzilla.kernel.org/show_bug.cgi?id=60749
Alan <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |CLOSED
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug 60749] Do not need to link against -lm for fabs*()
[not found] ` <bug-60749-11311-3bo0kxnWaOQUvHkbgXJLS5sdmw4N0Rt+2LY78lusg7I@public.gmane.org/>
` (3 preceding siblings ...)
2013-11-13 16:08 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
@ 2014-03-10 13:26 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
4 siblings, 0 replies; 6+ messages in thread
From: bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r @ 2014-03-10 13:26 UTC (permalink / raw)
To: linux-man-u79uwXL29TY76Z2rM5mHXA
https://bugzilla.kernel.org/show_bug.cgi?id=60749
--- Comment #4 from Michael Kerrisk <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> ---
Walter Harms pointed out on linux-man that what is going on here is that
gcc implements some functions (many of them are math functions) as built-ins.
There is a list here: http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
When the function is a compiled as a gcc built-in, then it is not
necessary link against the corresponding library.
However, I'm unwilling to add that level of detail about a specific
compiler to the various manual pages.
On Thu, Aug 15, 2013 at 10:36 PM, <bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r@public.gmane.org> wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=60749
>
> Bug ID: 60749
> Summary: Do not need to link against -lm for fabs*()
> Product: Documentation
> Version: unspecified
> Hardware: All
> OS: Linux
> Status: NEW
> Severity: low
> Priority: P1
> Component: man-pages
> Assignee: documentation_man-pages-ztI5WcYan/vQLgFONoPN62D2FQJk+8+b@public.gmane.org
> Reporter: orion-CVdf0l11yl+B+jHODAdFcQ@public.gmane.org
> Regression: No
>
> From the fabs(3) man page:
>
> SYNOPSIS
> #include <math.h>
>
> double fabs(double x);
> float fabsf(float x);
> long double fabsl(long double x);
>
> Link with -lm.
>
>
> At least on RHEL5+ one does not appear to need to link with -lm.
>
> # cat fabs.c
> #include <math.h>
> #include <stdlib.h>
> #include <stdio.h>
>
> int main(int argc, char **argv)
> {
> printf("%f\n",fabs(atof(argv[1])));
> printf("%f\n",fabsf((float)atof(argv[1])));
> printf("%Lf\n",fabsl((long double)atof(argv[1])));
> return 0;
> }
> # gcc -g -Wall fabs.c
> # ./a.out -2.5
> 2.500000
> 2.500000
> 2.500000
> # gcc -v
> Using built-in specs.
> Target: x86_64-redhat-linux
> Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
> --infodir=/usr/share/info --enable-shared --enable-threads=posix
> --enable-checking=release --with-system-zlib --enable-__cxa_atexit
> --disable-libunwind-exceptions --enable-libgcj-multifile
> --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk
> --disable-dssi --disable-plugin
> --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic
> --host=x86_64-redhat-linux
> Thread model: posix
> gcc version 4.1.2 20080704 (Red Hat 4.1.2-54)
>
> --
> You are receiving this mail because:
> You are watching the assignee of the bug.
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end of thread, other threads:[~2014-03-10 13:26 UTC | newest]
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2013-08-15 20:36 [Bug 60749] New: Do not need to link against -lm for fabs*() bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
[not found] ` <bug-60749-11311-3bo0kxnWaOQUvHkbgXJLS5sdmw4N0Rt+2LY78lusg7I@public.gmane.org/>
2013-08-29 10:09 ` [Bug 60749] " bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2013-08-29 10:10 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2013-11-13 16:08 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
2013-11-13 16:08 ` bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r
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