it seems that any program that i try to compile (using gcc) that needs the math.h library doesnt have the required functions.

when i use the following program: (sorry i dont know how to put it in the boxes and im in a hurry)
#include <stdio.h>
#include <math.h>

int main()
{
float s1=sin(M_PI/2);
float s2=cos(M_PI/2);
float s3=tan(M_PI/2);
return 1;
}


i get: (again, sry)
/tmp/ccia1gtc.o: In function `main':
test.c.text+0x2c): undefined reference to `sin'
test.c.text+0x46): undefined reference to `cos'
test.c.text+0x60): undefined reference to `tan'
collect2: ld returned 1 exit status

any suggestions?

Are you compiling with the "-lm" flag?

no, i wasnt. that made it all work. thank you so much. what does the lm flag do, tho?

I am trying to brush up on my C++ programming that I learned in school. I'm using Ubuntu (Edgy) on a laptop as my learning tool.

My programs uses the following form:

//practice.cpp
#include <iostream>
#include <math>
using namespace std;

int main ()
{
float numberInput = (float) 0.0;
float square = (float) 0.0;
float sqRoot = (float) 0.0;

cout << "Enter a number: ";
cin >> numberInput;

square = (float) pow(numberInput, 2);
sqRoot = (float) sqrt(numberInput);

cout << "Square of << numberInput << " = " << square << endl;
cout << "Square Root of " << numberInput << " = " << sqrt << end;

return 0;
}

When I do a "locate math.h" in my terminal window, it shows me:

/usr/include/math.h


I tried: g++ -o practice -lm math.h practice.cpp
That did'nt work!

I tried: g++ -o practice -lm /user/include/math.h practice.cpp
That did'nt work!

Assuming the /usr/include/math.h file is the correct one, what is the correct syntax for linking the math library to the compiler?

I tried googling for it, but had no luck so far.