| 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 | } |