Thread: testing math.h

I wrote this snippet to try some simple math but it appears I am the simple one:

Code:

// Test for math.h
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>

int main(void)
{
    double E;
    double M;
    double V;
    M = .25;
    V = 1400;
    E = M*(pow(V,2))/2;
    printf("Kinetic energy is %f", E);
    getchar();
    return(0);
}

Code:

/*
compiler error:
gcc -Wall -o "mathtest" "mathtest.c" (in directory: /home/paul/Documents/C-files)
/tmp/ccEbPuLK.o: In function `main':
mathtest.c:(.text+0x45): undefined reference to `pow'
collect2: error: ld returned 1 exit status
Compilation failed.
*/

I thought pow() was defined in math.h

I am using Ubuntu 14.04.1, coding in C99, using Geany IDE.
Am I ignorant? Am I missing the Math header file?

Paul

Am I missing the Math header file?

No, but you need to add the math library to the compile line ( -lm ). Those are linker errors, not compile errors so the header file was found.

Jim

jimblumberg,

I am using an IDE - I don't understand how I am supposed to add the math library to the compile line.
I don't add any of the other libraries - it is supposed to be done by the software...??

Paul

Grumpy,
So how do I add the math library to the compile line when using Geany in Ubuntu 14.04.1?

I also don't use Geany (by the way, i use Anjuta), but i found a statement on web.

Add -lm option to the end of gcc command line in the Build -> Set Build Commands menu.

Link: c - How to link math.h library in geany? - Stack Overflow