ack/lang/cem/libcc.ansi/core/math/hypot.c
David Given d1cdb07719 Realise that the libc core can safely call other libc core functions, even if
they're not defined in the core: so putw() can call stdio stuff, for example.
So the earlier concept of pureness isn't necessary. Rename accordingly.
2018-06-21 23:24:23 +02:00

44 lines
667 B
C

/*
* (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>
/* $Id$ */
double
hypot(double x, double 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);
}
struct complex
{
double r, i;
};
double
cabs(struct complex p_compl)
{
return hypot(p_compl.r, p_compl.i);
}