minix/lib/libc/other/hypot.c

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2005-04-21 16:53:53 +02:00
/*
* (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 ));
/* $Header$ */
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);
}