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math functions not working on Linux [message #524941]

Sun, 04 April 2010 14:52

Nelio

Messages: 2
Registered: April 2010

Junior Member

Hello,

I'm trying to test simple programs with math functions (sqrt, pow, exp, etc.) in Eclipse for C/C++ in a Ubuntu S.O. A simple program like this doesn't work:

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

int main () {
double param, result;
param = 5.0;
result = exp (param);
printf ("The exponential value of %lf is %lf.\n", param, result );
return 0;
}

Compiler says something like undefined reference to `exp'

Se same test works perfectly in Windows, but not in Ubuntu. What am I missing?

Another information: if I use exp(5.0) instead of exp(param), the program works!!

Thank you
Nelio

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Re: math functions not working on Linux [message #524957 is a reply to message #524941]

Sun, 04 April 2010 19:08

Nick Schweyer

Messages: 175
Registered: July 2009

Senior Member

I had the same problem:
you have to tell the linker to use the math library by setting -m

Niko

Eclipse-CDT Version: 2019-12 (4.14.0), Win10 64bit

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Re: math functions not working on Linux [message #525841 is a reply to message #524957]

Wed, 07 April 2010 23:37

Nelio

Messages: 2
Registered: April 2010

Junior Member

I did what you said, but now a new error is appearing. Suppose "testproj" is the project name:

Errors (1 item)
unrecognised emulation mode: -otestproj

Location: line 0

Type: C/C++ Problem

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Re: math functions not working on Linux [message #526091 is a reply to message #525841]

Thu, 08 April 2010 16:34

Don Porges

Messages: 13
Registered: July 2009

Junior Member

He made a typo: the flag you want is -lm not -m. Although you can do with that just by entering "m" in the Libraries list of the Linker settings.

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Re: math functions not working on Linux [message #903299 is a reply to message #526091]

Thu, 23 August 2012 01:10

Esdras Adriano

Messages: 2
Registered: August 2012
Location: Brasil

Junior Member

Hello,

I also had the same problem as you guys and I'm using the Eclipse version 3.7.2 on ubuntu 12.04. I solved the problem by entering the command -lm in:
Project>> Properties >> Cross GCC linker>> Miscellaneous >>Other objects.

bye and enjoy.

Esdras.

[Updated on: Thu, 23 August 2012 01:11]

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