1 /* @(#)sinh.c 4.1 12/25/82 */ 2 3 /* 4 sinh(arg) returns the hyperbolic sine of its floating- 5 point argument. 6 7 The exponential function is called for arguments 8 greater in magnitude than 0.5. 9 10 A series is used for arguments smaller in magnitude than 0.5. 11 The coefficients are #2029 from Hart & Cheney. (20.36D) 12 13 cosh(arg) is computed from the exponential function for 14 all arguments. 15 */ 16 17 double exp(); 18 19 static double p0 = -0.6307673640497716991184787251e+6; 20 static double p1 = -0.8991272022039509355398013511e+5; 21 static double p2 = -0.2894211355989563807284660366e+4; 22 static double p3 = -0.2630563213397497062819489e+2; 23 static double q0 = -0.6307673640497716991212077277e+6; 24 static double q1 = 0.1521517378790019070696485176e+5; 25 static double q2 = -0.173678953558233699533450911e+3; 26 27 double 28 sinh(arg) 29 double arg; 30 { 31 double temp, argsq; 32 register sign; 33 34 sign = 1; 35 if(arg < 0) { 36 arg = - arg; 37 sign = -1; 38 } 39 40 if(arg > 21.) { 41 temp = exp(arg)/2; 42 if (sign>0) 43 return(temp); 44 else 45 return(-temp); 46 } 47 48 if(arg > 0.5) { 49 return(sign*(exp(arg) - exp(-arg))/2); 50 } 51 52 argsq = arg*arg; 53 temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg; 54 temp /= (((argsq+q2)*argsq+q1)*argsq+q0); 55 return(sign*temp); 56 } 57 58 double 59 cosh(arg) 60 double arg; 61 { 62 if(arg < 0) 63 arg = - arg; 64 if(arg > 21.) { 65 return(exp(arg)/2); 66 } 67 68 return((exp(arg) + exp(-arg))/2); 69 } 70