| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package math |
| |
| import math "math" |
| export sinh, cosh |
| |
| /* |
| * sinh(arg) returns the hyperbolic sine of its floating- |
| * point argument. |
| * |
| * The exponential func is called for arguments |
| * greater in magnitude than 0.5. |
| * |
| * A series is used for arguments smaller in magnitude than 0.5. |
| * The coefficients are #2029 from Hart & Cheney. (20.36D) |
| * |
| * cosh(arg) is computed from the exponential func for |
| * all arguments. |
| */ |
| |
| const |
| ( |
| p0 = -0.6307673640497716991184787251e+6; |
| p1 = -0.8991272022039509355398013511e+5; |
| p2 = -0.2894211355989563807284660366e+4; |
| p3 = -0.2630563213397497062819489e+2; |
| q0 = -0.6307673640497716991212077277e+6; |
| q1 = 0.1521517378790019070696485176e+5; |
| q2 = -0.173678953558233699533450911e+3; |
| ) |
| |
| func |
| sinh(arg float64) float64 |
| { |
| var temp, argsq float64; |
| var sign bool; |
| |
| sign = false; |
| if arg < 0 { |
| arg = -arg; |
| sign = true; |
| } |
| |
| switch true { |
| case arg > 21: |
| temp = exp(arg)/2; |
| |
| case arg > 0.5: |
| temp = (exp(arg) - exp(-arg))/2; |
| |
| default: |
| argsq = arg*arg; |
| temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg; |
| temp = temp/(((argsq+q2)*argsq+q1)*argsq+q0); |
| } |
| |
| if sign { |
| temp = -temp; |
| } |
| return temp; |
| } |
| |
| func |
| cosh(arg float64) float64 |
| { |
| if arg < 0 { |
| arg = - arg; |
| } |
| if arg > 21 { |
| return exp(arg)/2; |
| } |
| return (exp(arg) + exp(-arg))/2; |
| } |