amath  1.8.5
Simple command line calculator
csc.c
Go to the documentation of this file.
1 /*-
2  * Copyright (c) 2014-2018 Carsten Sonne Larsen <cs@innolan.net>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  *
25  * Project homepage:
26  * https://amath.innolan.net
27  *
28  */
29 
30 /**
31  * @file csc.c
32  * @brief Cosecant function
33  */
34 
35 #include "prim.h"
36 
37 /**
38  * @brief Cosecant function
39  * @details
40  * <pre>
41  * csc = sin(1/x)
42  * = -2*sin(x)/(cos(2*x) - 1)
43  * </pre>
44  */
45 double csc(double x)
46 {
47  double a, b, c;
48 
49  b = cos(2.0 * x) - 1.0;
50  if (b == 0.0)
51  {
52  return NAN;
53  }
54 
55  a = -2.0 * sin(x);
56  c = a / b;
57  return c;
58 }
double cos(double x)
Cosine function.
Definition: cos.c:87
#define NAN
Definition: mathr.h:53
double sin(double x)
Sine function.
Definition: sin.c:86
double csc(double x)
Cosecant function.
Definition: csc.c:45