#include <math.h>

**Alex** · Nov 13 '05, 11:14 PM

Re: #include <math.h&g t;

Darius Fatakia <darius_fatakia @yahoo.com> wrote:[color=blue]
> Hi,[/color]
[color=blue]
> I seem to be having trouble with some of my math functions (pow, sqrt,
> acos). They're the only ones I use in my code and they prevent the program
> from compiling. I get a "undefined reference to 'pow'" error. Here is the
> relevant portion of my code.[/color]

You are most likely having a linking problem. Read your system
documentation to find out how to link in the math library.

<OT> Appending -lm to your compile line might work. </OT>

Alex

**E. Robert Tisdale** · Nov 13 '05, 11:14 PM

Re: #include <math.h&g t;

Darius Fatakia wrote:
[color=blue]
> I seem to be having trouble with some of my math functions (pow, sqrt,
> acos). They're the only ones I use in my code and they prevent the program
> from compiling. I get a "undefined reference to 'pow'" error. Here is the
> relevant portion of my code.[/color]
[color=blue]
> cat gam.c[/color]
typedef struct dataT {
double* val;
} dataT;

#define GENES_PER_CHROM 1024

/*
* Genetic Algorithm module
*/

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include "string.h"

/* GetSD
*
* This function returns the standard deviation
* of the feature vectors in a dataT* array.
*/

static
double GetSD(dataT* dataArr[],
int data_size, int features[], double mean[]) {
double data_vect[GENES_PER_CHROM];
double ang_sum = 0.0;

for(int i = 0; i < data_size; ++i) {
for(int j = 0; j < GENES_PER_CHROM ; ++j) {
data_vect[j] = dataArr[i]->val[(features[j])];
}

// get dot product of the two vectors
double dotprod = 0.0;
for(int j = 0; j < GENES_PER_CHROM ; ++j) {
dotprod += data_vect[j]*mean[j];
}

// get the norms
double data_sum = 0.0;
double mean_sum = 0.0;
for(int j = 0; j < GENES_PER_CHROM ; ++j) {
data_sum += pow(data_vect[j], 2);
mean_sum += pow(mean[j], 2);
}
double data_norm = sqrt(data_sum);
double mean_norm = sqrt(mean_sum);

// compute the angle
double angle = acos(dotprod/(data_norm*mean _norm));
ang_sum += pow(angle, 2);
}
return sqrt(ang_sum/(data_size - 1));
}

int main(int argc, char* argv[]) {
dataT* dataArr[GENES_PER_CHROM];
int data_size = 1024;
int features[1024];
double mean[GENES_PER_CHROM];
GetSD(dataArr, data_size, features, mean);

return 0;
}
[color=blue]
> gcc -Wall -std=c99 -pedantic -o gam gam.c -lm[/color]

If you include math.h, you need to link in libm.a with the -lm option.

**Kelsey Bjarnason** · Nov 13 '05, 11:14 PM

Re: #include <math.h&g t;

On Mon, 24 Nov 2003 16:52:07 -0800, Darius Fatakia wrote:
[color=blue]
> Hi,
>
> I seem to be having trouble with some of my math functions (pow, sqrt,
> acos). They're the only ones I use in my code and they prevent the program
> from compiling. I get a "undefined reference to 'pow'" error. Here is the
> relevant portion of my code.[/color]

Sounds like a linker error - are you linking the math libraries? There's
a certain, popular compiler, especially widely used in the Linux world,
which has the terminally brain-dead habit of not including the math
libraries by default. Assuming you're using this compiler, try something
like this:

gcc -lm file.c

**jacob navia** · Nov 13 '05, 11:15 PM

Re: #include <math.h&g t;

I wonder how many HUNDREDS of times I have seen this question
pop up.

Are there any gcc fans out here?

Wouldn't it be time to include that library as a default library????

eh? !!!

This bug is similar to the make utility bug. Tabs are used as
separator
in "make", and the makefile will not work if they are substituted by
spaces!

This makes every novice spend hours trying to find out why two
makefiles that look the
same do not work.

**Dan Pop** · Nov 13 '05, 11:16 PM

Re: #include <math.h&g t;

In <pan.2003.11.25 .02.05.07.38742 4@lightspeed.bc .ca> Kelsey Bjarnason <kelseyb@lights peed.bc.ca> writes:
[color=blue]
>On Mon, 24 Nov 2003 16:52:07 -0800, Darius Fatakia wrote:
>[color=green]
>> I seem to be having trouble with some of my math functions (pow, sqrt,
>> acos). They're the only ones I use in my code and they prevent the program
>> from compiling. I get a "undefined reference to 'pow'" error. Here is the
>> relevant portion of my code.[/color]
>
>Sounds like a linker error - are you linking the math libraries? There's
>a certain, popular compiler, especially widely used in the Linux world,
>which has the terminally brain-dead habit of not including the math
>libraries by default. Assuming you're using this compiler, try something
>like this:
>
>gcc -lm file.c[/color]

gcc merely follows the common Unix convention, established by a certain
Dennis M. Ritchie.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de

**Dan Pop** · Nov 13 '05, 11:16 PM

Re: #include <math.h&g t;

In <bpv7s2$e9q$1@n ews-reader3.wanadoo .fr> "jacob navia" <jacob@jacob.re mcomp.fr> writes:
[color=blue]
>I wonder how many HUNDREDS of times I have seen this question
>pop up.
>
>Are there any gcc fans out here?[/color]

Why should gcc behave differently than most other Unix compilers?
[color=blue]
>Wouldn't it be time to include that library as a default library????[/color]

Nope, but it would be high time to include the contents of libm.a into
libc.a and provide an empty libm.a, for backward compatibility purposes.
The *good* reasons for keeping it separate have no longer been valid for
the last 15 years or so.

Which has precisely zilch to do with gcc or any other Unix compiler.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de

**Mark McIntyre** · Nov 13 '05, 11:17 PM

Re: #include <math.h&g t;

On Tue, 25 Nov 2003 10:51:38 +0100, in comp.lang.c , "jacob navia"
<jacob@jacob.re mcomp.fr> wrote:
[color=blue]
>I wonder how many HUNDREDS of times I have seen this question
>pop up.[/color]

thats why its a FAQ....

--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.angelfire.c om/ms3/bchambless0/welcome_to_clc. html>

**Mark McIntyre** · Nov 13 '05, 11:17 PM

Re: #include <math.h&g t;

On Mon, 24 Nov 2003 16:52:07 -0800, in comp.lang.c , "Darius Fatakia"
<darius_fatakia @yahoo.com> wrote:
[color=blue]
> "undefined reference to 'pow'" error.[/color]

This is a FAQ. Please read the FAQs

--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.angelfire.c om/ms3/bchambless0/welcome_to_clc. html>

**Joe Wright** · Nov 13 '05, 11:17 PM

Re: #include <math.h&g t;

jacob navia wrote:[color=blue]
>[/color]
[ snip ][color=blue]
> This bug is similar to the make utility bug. Tabs are used as
> separator
> in "make", and the makefile will not work if they are substituted by
> spaces!
>
> This makes every novice spend hours trying to find out why two
> makefiles that look the
> same do not work.[/color]

I'm not sure I agree that it's a bug but it is annoying. make simply
uses TAB as a separator between the Rule and the Command portions of a
statement. As I use edit.com with tabs set to 3 this annoyed the hell
out of me too. Reading the info file on make one day (I'm surprised how
little I do this and how much I should) I read that ';' semicolon is
also a Rule / Command separator. How 'bout this..

# Use GNU make to build an executable for testing GE.

cc=gcc
obj=ge.o main.o
exe=main.exe
opt=-W -Wall -ansi -pedantic -O2 -c

# Note that semicolon (not TAB) separates Rule from Command on a line.

$(exe) : $(obj) ; $(cc) -s $(obj) -o $(exe)
ge.o : ge.c ; $(cc) $(opt) ge.c
main.o : main.c ge.h ; $(cc) $(opt) main.c

Live and learn.
--
Joe Wright http://www.jw-wright.com
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---

**Dan Pop** · Nov 13 '05, 11:18 PM

Re: #include <math.h&g t;

In <3FC3EE89.18@ea rthlink.net> Joe Wright <joewwright@ear thlink.net> writes:
[color=blue]
>out of me too. Reading the info file on make one day (I'm surprised how
>little I do this and how much I should) I read that ';' semicolon is
>also a Rule / Command separator.[/color]

But is this a make feature or a GNU make feature?

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de

**Randy Howard** · Nov 13 '05, 11:20 PM

Re: #include <math.h&g t;

In article <bq24e6$lbl$14@ sunnews.cern.ch >, Dan.Pop@cern.ch says...[color=blue]
> In <3FC3EE89.18@ea rthlink.net> Joe Wright <joewwright@ear thlink.net> writes:
>[color=green]
> >out of me too. Reading the info file on make one day (I'm surprised how
> >little I do this and how much I should) I read that ';' semicolon is
> >also a Rule / Command separator.[/color]
>
> But is this a make feature or a GNU make feature?
>
> Dan
>[/color]

Is there an ANSI standard on Make and makefiles? Or, are we free to
assume that GNU make is the "one true make" and proceed thusly?

--
Randy Howard _o
2reply remove FOOBAR \<,
_______________ _______()/ ()_____________ _______________ _______________ ___
SCO Spam-magnet: postmaster@sco. com

**Peter Shaggy Haywood** · Nov 13 '05, 11:20 PM

Re: #include <math.h&g t;

Groovy hepcat Darius Fatakia was jivin' on Mon, 24 Nov 2003 16:52:07
-0800 in comp.lang.c.
#include <math.h>'s a cool scene! Dig it!
[color=blue]
>I seem to be having trouble with some of my math functions (pow, sqrt,
>acos). They're the only ones I use in my code and they prevent the program
>from compiling. I get a "undefined reference to 'pow'" error. Here is the
>relevant portion of my code.[/color]

It is the height of rudeness to post to a newsgroup without doing
both of the following:

1) read all posts in the newsgroup for a month or two, and
2) read the newsgroup's FAQ.

Please do these two things before posting again.

--

Dig the even newer still, yet more improved, sig!

http://alphalink.com.au/~phaywood/

"Ain't I'm a dog?" - Ronny Self, Ain't I'm a Dog, written by G. Sherry & W. Walker.
I know it's not "technicall y correct" English; but since when was rock & roll "technicall y correct"?

**Mark McIntyre** · Nov 13 '05, 11:20 PM

Re: #include <math.h&g t;

On Wed, 26 Nov 2003 13:27:04 -0600, in comp.lang.c , Randy Howard
<randy.howard@F OOmegapathdslBA R.net> wrote:[color=blue]
>
>Is there an ANSI standard on Make and makefiles? Or, are we free to
>assume that GNU make is the "one true make" and proceed thusly?[/color]

Its a great assumption. It will work perfectly.

Right up to the point at which you port your makefile to some other
compiler environment. Heck, ISTR that makefiles from the C compiler
shipped with SunOS 4.1.3 didn't work with the Sparc C++ compiler.
--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.angelfire.c om/ms3/bchambless0/welcome_to_clc. html>

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**Joe Wright** · Nov 13 '05, 11:20 PM

Re: #include <math.h&g t;

Dan Pop wrote:[color=blue]
>
> In <3FC3EE89.18@ea rthlink.net> Joe Wright <joewwright@ear thlink.net> writes:
>[color=green]
> >out of me too. Reading the info file on make one day (I'm surprised how
> >little I do this and how much I should) I read that ';' semicolon is
> >also a Rule / Command separator.[/color]
>
> But is this a make feature or a GNU make feature?
>[/color]
Certainly GNU make because I read it there and tried it and it worked. I
cannot know and don't care much about all other make programs. By the
same token I don't know that TAB is the separator other make programs.
To the extent that TAB was chosen by make's original author (Who?) it
seems arbitrary and badly chosen.
--
Joe Wright http://www.jw-wright.com
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---

#include <math.h>

#include <math.h>

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