github.com/afumu/libc@v0.0.6/musl/src/complex/ctanhf.c (about)

     1  /* origin: FreeBSD /usr/src/lib/msun/src/s_ctanhf.c */
     2  /*-
     3   * Copyright (c) 2011 David Schultz
     4   * All rights reserved.
     5   *
     6   * Redistribution and use in source and binary forms, with or without
     7   * modification, are permitted provided that the following conditions
     8   * are met:
     9   * 1. Redistributions of source code must retain the above copyright
    10   *    notice unmodified, this list of conditions, and the following
    11   *    disclaimer.
    12   * 2. Redistributions in binary form must reproduce the above copyright
    13   *    notice, this list of conditions and the following disclaimer in the
    14   *    documentation and/or other materials provided with the distribution.
    15   *
    16   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
    17   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    18   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
    19   * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
    20   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
    21   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    22   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    23   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    24   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
    25   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    26   */
    27  /*
    28   * Hyperbolic tangent of a complex argument z.  See s_ctanh.c for details.
    29   */
    30  
    31  #include "complex_impl.h"
    32  
    33  float complex ctanhf(float complex z)
    34  {
    35  	float x, y;
    36  	float t, beta, s, rho, denom;
    37  	uint32_t hx, ix;
    38  
    39  	x = crealf(z);
    40  	y = cimagf(z);
    41  
    42  	GET_FLOAT_WORD(hx, x);
    43  	ix = hx & 0x7fffffff;
    44  
    45  	if (ix >= 0x7f800000) {
    46  		if (ix & 0x7fffff)
    47  			return CMPLXF(x, (y == 0 ? y : x * y));
    48  		SET_FLOAT_WORD(x, hx - 0x40000000);
    49  		return CMPLXF(x, copysignf(0, isinf(y) ? y : sinf(y) * cosf(y)));
    50  	}
    51  
    52  	if (!isfinite(y))
    53  		return CMPLXF(ix ? y - y : x, y - y);
    54  
    55  	if (ix >= 0x41300000) { /* x >= 11 */
    56  		float exp_mx = expf(-fabsf(x));
    57  		return CMPLXF(copysignf(1, x), 4 * sinf(y) * cosf(y) * exp_mx * exp_mx);
    58  	}
    59  
    60  	t = tanf(y);
    61  	beta = 1.0 + t * t;
    62  	s = sinhf(x);
    63  	rho = sqrtf(1 + s * s);
    64  	denom = 1 + beta * s * s;
    65  	return CMPLXF((beta * rho * s) / denom, t / denom);
    66  }