amath/src/cplex/casinh.c

56 lines
2.0 KiB
C

/*-
* Copyright (c) 2014-2021 Carsten Sonne Larsen <cs@innolan.net>
* 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 AUTHOR ``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 AUTHOR 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.
*
* Project homepage:
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*
*/
#include "prim.h"
/**
* @brief Inverse hyperbolic sine of complex number
* @details
* Inverse hyperbolic sine expressed using complex logarithms:
* <pre>
* asinh(z) = log(z + sqrt(z*z + 1))
*
* With branch cuts: -i INF to -i and i to i INF
*
* Domain: -INF to INF
* Range: -INF to INF
* </pre>
* More info is available at Wikipedia: <BR>
* https://wikipedia.org/wiki/Inverse_hyperbolic_function#Logarithmic_representation
*/
complex casinh(complex z)
{
// TODO: Fix branch cuts
complex one = cpack(1.0, 0.0);
complex a = cadd(cmul(z, z), one);
complex b = cadd(z, csqrt(a));
complex w = clog(b);
return w;
}