mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-27 14:50:23 +00:00
107 lines
3.3 KiB
C
107 lines
3.3 KiB
C
/* $NetBSD: cproj.c,v 1.3 2010/09/20 17:51:38 christos Exp $ */
|
|
|
|
/*-
|
|
* Copyright (c) 2010 The NetBSD Foundation, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
* imported and modified include for newlib 2010/10/03
|
|
* Marco Atzeri <marco_atzeri@yahoo.it>
|
|
*/
|
|
|
|
/*
|
|
FUNCTION
|
|
<<cproj>>, <<cprojf>>--- Riemann sphere projection
|
|
|
|
INDEX
|
|
cproj
|
|
INDEX
|
|
cprojf
|
|
|
|
ANSI_SYNOPSIS
|
|
#include <complex.h>
|
|
double complex cproj(double complex <[z]>);
|
|
float complex cprojf(float complex <[z]>);
|
|
|
|
|
|
DESCRIPTION
|
|
These functions compute a projection of <[z]> onto the Riemann
|
|
sphere: <[z]> projects to <[z]> except that all complex infinities
|
|
(even those with one infinite part and one NaN part) project
|
|
to positive infinity on the real axis. If <[z]> has an infinite part,
|
|
then <<cproj>>(<[z]>) is equivalent to
|
|
|
|
INFINITY + I * copysign(0.0, cimag(z))
|
|
|
|
<<cprojf>> is identical to <<cproj>>, except that it performs
|
|
its calculations on <<floats complex>>.
|
|
|
|
RETURNS
|
|
The cproj functions return the value of the projection onto
|
|
the Riemann sphere.
|
|
|
|
PORTABILITY
|
|
<<cproj>> and <<cprojf>> are ISO C99
|
|
|
|
QUICKREF
|
|
<<cproj>> and <<cprojf>> are ISO C99
|
|
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
/*__RCSID("$NetBSD: cproj.c,v 1.3 2010/09/20 17:51:38 christos Exp $"); */
|
|
|
|
#include <complex.h>
|
|
#include <math.h>
|
|
|
|
#include "../common/fdlibm.h"
|
|
|
|
/*
|
|
* cproj(double complex z)
|
|
*
|
|
* These functions return the value of the projection (not stereographic!)
|
|
* onto the Riemann sphere.
|
|
*
|
|
* z projects to z, except that all complex infinities (even those with one
|
|
* infinite part and one NaN part) project to positive infinity on the real axis.
|
|
* If z has an infinite part, then cproj(z) shall be equivalent to:
|
|
*
|
|
* INFINITY + I * copysign(0.0, cimag(z))
|
|
*/
|
|
double complex
|
|
cproj(double complex z)
|
|
{
|
|
double_complex w = { .z = z };
|
|
|
|
if (isinf(creal(z)) || isinf(cimag(z))) {
|
|
#ifdef __INFINITY
|
|
REAL_PART(w) = __INFINITY;
|
|
#else
|
|
REAL_PART(w) = INFINITY;
|
|
#endif
|
|
IMAG_PART(w) = copysign(0.0, cimag(z));
|
|
}
|
|
|
|
return (w.z);
|
|
}
|