Error: undefined reference to math functions

Question

This is function pointer program: demo.c

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

void tabulate(double (*f)(double), double first, double last, double incr);

int main(void) {

    double final, increment, initial;

    printf("Enter initial value: ");
    scanf("%lf", &initial);

    printf("Enter final value: ");
    scanf("%lf", &final);

    printf("Enter increment: ");
    scanf("%lf", &increment);

    printf("\n      x       cos(x)"
           "\n   -------    -------\n");
    tabulate(cos, initial, final, increment);
    return 0;
}

void tabulate(double (*f)(double), double first, double last, double incr) {
    double x;
    int i, num_intervals;

    num_intervals = ceil((last - first)/incr);
    for(i=0; i<=num_intervals; i++) {
        x = first + i * incr;
        printf("%10.5f %10.5f\n", x, (*f)(x));
    }
}

When I try to run this code, got this message:

/tmp/ccQ4IZeD.o: In function `main':
demo.c:(.text+0x92): undefined reference to `cos'
/tmp/ccQ4IZeD.o: In function `tabulate':
demo.c:(.text+0xe3): undefined reference to `ceil'
collect2: error: ld returned 1 exit status

What does it means, because cos and ceil is <math.h> file function. Is this is because of OS (ubuntu 13.10 32-bits), because this program is work on else system.

If it yes, then what solution is to run on my system.

You also need to link with the `math` library, pass `-lm` to your compiler. — Kninnug, Dec 18 '13 at 17:33
@Rohit are you putting `-lm` after your source file, for example `gcc demo.c -lm`. — Shafik Yaghmour, Dec 18 '13 at 17:39

score 9 · Answer 1 · answered Dec 18 '13 at 17:34

9

You have to use -lm at link time.

answered Dec 18 '13 at 17:34

jmlemetayer

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score 4 · Answer 2 · answered Dec 18 '13 at 19:18

4

Due to math library are not integrated in the standard gcc library because of integration issues with the kernel. you have to use -lm while compiling the code

answered Dec 18 '13 at 19:18

Ganesh Kale

51
3

score 1 · Answer 3 · answered Dec 18 '13 at 17:34

1

This is because your math library functions are not linked with the program. To link it compile with -lm flag.

answered Dec 18 '13 at 17:34

haccks

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Error: undefined reference to math functions

3 Answers3