hello all , I am new to C programming and trying to learn by working some online tutorials. I am working on a linux OS ( Ubuntu ) . so the program is to calculate a table of sine values and I typed in the code pretty much the way it was show in the tutorial, the code is shown below: Code: /* Written: Winter 1995 */ #include < stdio.h> #include < math.h> void main() { int angle_degree; double angle_radian, pi, value; /* Print a header */ printf ("\nCompute a table of the sine function\n\n"); /* obtain pi once for all */ /* or just use pi = M_PI, where M_PI is defined in math.h */ pi = 4.0*atan(1.0); printf ( " Value of PI = %f \n\n", pi ); printf ( " angle Sine \n" ); angle_degree=0; /* initial angle value */ /* scan over angle */ while ( angle_degree <= 360 ) /* loop until angle_degree > 360 */ { angle_radian = pi * angle_degree/180.0 ; value = sin(angle_radian); printf ( " %3d %f \n ", angle_degree, value ); angle_degree = angle_degree + 10; /* increment the loop index */ } } When I try to complile the program by typing $ gcc program_name.c I get the following error : /tmp/cciKZE0g.o: In function `main': sine.c.text+0x58): undefined reference to `sin' collect2: ld returned 1 exit status what does this mean ?? what should I do ? can any one help ? thanks , raurava

In C, which you are using, sin takes a double as an argument, not a float. Use sinf for floats. In C++, the functions are overloaded, so will work. Refer to your documentation for the functions you use.