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 #include <math.h> 16 #include <errno.h> 17 18 static double p0 = -0.6307673640497716991184787251e+6; 19 static double p1 = -0.8991272022039509355398013511e+5; 20 static double p2 = -0.2894211355989563807284660366e+4; 21 static double p3 = -0.2630563213397497062819489e+2; 22 static double q0 = -0.6307673640497716991212077277e+6; 23 static double q1 = 0.1521517378790019070696485176e+5; 24 static double q2 = -0.173678953558233699533450911e+3; 25 26 double sinh(double arg)27sinh(double arg) 28 { 29 double temp, argsq; 30 int sign; 31 32 sign = 1; 33 if(arg < 0) { 34 arg = - arg; 35 sign = -1; 36 } 37 if(arg > 21) { 38 if(arg >= HUGE_VAL){ 39 errno = ERANGE; 40 temp = HUGE_VAL; 41 } else 42 temp = exp(arg)/2; 43 if(sign > 0) 44 return temp; 45 else 46 return -temp; 47 } 48 49 if(arg > 0.5) 50 return sign*(exp(arg) - exp(-arg))/2; 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 cosh(double arg)59cosh(double arg) 60 { 61 if(arg < 0) 62 arg = - arg; 63 if(arg > 21) { 64 if(arg >= HUGE_VAL){ 65 errno = ERANGE; 66 return HUGE_VAL; 67 } else 68 return(exp(arg)/2); 69 } 70 return (exp(arg) + exp(-arg))/2; 71 } 72