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

#define PI         3.141592653589793

#define TORAD(a)   ( (a)*PI/180.0 )             /* Convert degrees to radians */
#define TODEG(a)   ( (a)*180.0/PI )             /* Convert radians to degrees */


main( int argc, char *argv[] )
{

float viewx, viewy ;
float sizex, sizey ;


// info
fprintf(stderr, "\n viewsize, utility to calculate camera view angle \n" );
	
// get size:
	fprintf ( stderr, " Enter resolution [720x576]          : ");
	scanf("%fx%f" , &sizex , &sizey );
// get angle:
	fprintf ( stderr, " Enter horizontal viewing angle      : " );
	scanf("%f" , &viewx );

// calculate vertical angle
viewy = TODEG ( 2* atan( sizey  / sizex  * tan( TORAD(viewx)/2 ) ) );
fprintf ( stderr, " %fx%f , horizontal view is %f degrees\n" , sizex, sizey, viewx );
fprintf ( stderr, " Vertical view angle is  : %.03f \n" , viewy );

}