{{keywords>wiki library source code example reference}}
===== tan =====
<code c>
    double tan(double);
</code>
Returns the tangent of a radian angle x. 


===== C Sourcecode Example =====
compile with gcc tan.c -o tan **-lm**
<code c>
#include <stdio.h> /* including standard library */
//#include <windows.h> /* uncomment this for Windows */

#include <math.h> /* including math library */

int main( void )
{
    double x;
    x = 42;
    
    printf ("tan of %lf° is %lf\n", x, tan (x*3.1415/180));
    return 0;
}
</code>

==== output ====
   output:
   user@host:~$ ./tan 
   tan of 42.000000° is 0.900365