/* include the standard I/O function prototypes */
#include <stdio.h>

		/* define a structure for complex numbers,
		 * and make it a type */
typedef struct 
Complex_s
{
	double im, re;
} Complex;

static Complex
product_Complex( Complex a, Complex b )
{
	Complex prod;

	prod.re = a.re * b.re - a.im * b.im;
	prod.im = a.re * b.im + a.im * b.re;

	return prod;
}

static void
print_Complex( Complex z )
{
	printf( "( %f, %f )", z.im, z.re );
}

int
main()
{
		/* declare and initialize two 3D points */
	Complex x = { 1.0, 2.0 },
	        y = { 1.0, 1.0 };

	Complex z = product_Complex( x, y );

	printf( "product: " );
	print_Complex( z );
	printf( "\n" );

	return 0;
}