source: trunk/minix/lib/other/hypot.c@ 11

/*
 * (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 *
 * Author: Ceriel J.H. Jacobs
 */

#include <math.h>

struct complex {
        double r,i;
};

_PROTOTYPE(double hypot, (double x, double y ));
_PROTOTYPE(double cabs, (struct complex p_compl ));

/* $Header: /cvsup/minix/src/lib/other/hypot.c,v 1.1.1.1 2005/04/21 14:56:27 beng Exp $ */

double
hypot(x, y)
double x, y;
{
        /*      Computes sqrt(x*x+y*y), avoiding overflow */

        if (x < 0) x = -x;
        if (y < 0) y = -y;
        if (x > y) {
                double t = y;
                y = x;
                x = t;
        }
        /* sqrt(x*x+y*y) = sqrt(y*y*(x*x/(y*y)+1.0)) = y*sqrt(x*x/(y*y)+1.0) */
        if (y == 0.0) return 0.0;
        x /= y;
        return y*sqrt(x*x+1.0);
}

double
cabs(p_compl)
struct complex p_compl;
{
        return hypot(p_compl.r, p_compl.i);
}