Commit | Line | Data |
---|---|---|
18e5fa7e BJ |
1 | /* |
2 | sinh(arg) returns the hyperbolic sine of its floating- | |
3 | point argument. | |
4 | ||
5 | The exponential function is called for arguments | |
6 | greater in magnitude than 0.5. | |
7 | ||
8 | A series is used for arguments smaller in magnitude than 0.5. | |
9 | The coefficients are #2029 from Hart & Cheney. (20.36D) | |
10 | ||
11 | cosh(arg) is computed from the exponential function for | |
12 | all arguments. | |
13 | */ | |
14 | ||
15 | double exp(); | |
16 | ||
17 | static double p0 = -0.6307673640497716991184787251e+6; | |
18 | static double p1 = -0.8991272022039509355398013511e+5; | |
19 | static double p2 = -0.2894211355989563807284660366e+4; | |
20 | static double p3 = -0.2630563213397497062819489e+2; | |
21 | static double q0 = -0.6307673640497716991212077277e+6; | |
22 | static double q1 = 0.1521517378790019070696485176e+5; | |
23 | static double q2 = -0.173678953558233699533450911e+3; | |
24 | ||
25 | double | |
26 | sinh(arg) | |
27 | double arg; | |
28 | { | |
29 | double temp, argsq; | |
30 | register sign; | |
31 | ||
32 | sign = 1; | |
33 | if(arg < 0) { | |
34 | arg = - arg; | |
35 | sign = -1; | |
36 | } | |
37 | ||
38 | if(arg > 21.) { | |
39 | temp = exp(arg)/2; | |
40 | if (sign>0) | |
41 | return(temp); | |
42 | else | |
43 | return(-temp); | |
44 | } | |
45 | ||
46 | if(arg > 0.5) { | |
47 | return(sign*(exp(arg) - exp(-arg))/2); | |
48 | } | |
49 | ||
50 | argsq = arg*arg; | |
51 | temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg; | |
52 | temp /= (((argsq+q2)*argsq+q1)*argsq+q0); | |
53 | return(sign*temp); | |
54 | } | |
55 | ||
56 | double | |
57 | cosh(arg) | |
58 | double arg; | |
59 | { | |
60 | if(arg < 0) | |
61 | arg = - arg; | |
62 | if(arg > 21.) { | |
63 | return(exp(arg)/2); | |
64 | } | |
65 | ||
66 | return((exp(arg) + exp(-arg))/2); | |
67 | } |