sqrt

**modec** · 04-16-2003

Code:

#include <math.h>

float sqr(float a)
{
      return a*a;
}
float length(float x1,float y1,float x2,float y2)
{
      return sqrt(sqr(x2-x1)+sqr(y2-y1));
}

i get the following message from the compiler:

Code:

Undefined                       first referenced
 symbol                             in file
sqrt                                /var/tmp/ccHwDVgc.o
main                                /usr/local/lib/gcc-lib/sparc-sun-solaris2.7/2.95.2/crt1.o
ld: fatal: Symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status

I know that sqrt is defined as double sqrt(double).
Could someone help me with the casting?

**DavT** · 04-16-2003

As I see it you have two choices:

Code:

#include <math.h>

float sqr(float a)
{
  return a*a;
}

float length(float x1,float y1,float x2,float y2)
{
  return (float)sqrt((double)sqr(x2-x1)+(double)sqr(y2-y1));
}

or

Code:

#include <math.h>

double sqr(double a)
{
  return a*a;
}

double length(double x1,double y1,double x2,double y2)
{
  return sqrt(sqr(x2-x1)+sqr(y2-y1));
}

The choice is yours.

**kurz7** · 04-16-2003

dont forget to include the maths library when u compile
so something like:

gcc -Wall -ansi filename.c -o filename -lm

'l' as in 'L'

**modec** · 04-16-2003

Thanks a lot it works perfectly now. kurz7 do you know why i didn't have to include stdio in the gcc command for other programs?

Thread: sqrt

Thread Tools

Search Thread

Display

sqrt

Similar Threads

undefined reference to sqrt

"Undefined Reference" to pow and sqrt even though math.h header is there

sqrt() function help

SQRT Mystery...

how sqrt ?