1 #include <u.h> 2 #include <libc.h> 3 4 /* 5 * sinh(arg) returns the hyperbolic sine of its floating- 6 * point argument. 7 * 8 * The exponential function is called for arguments 9 * greater in magnitude than 0.5. 10 * 11 * A series is used for arguments smaller in magnitude than 0.5. 12 * The coefficients are #2029 from Hart & Cheney. (20.36D) 13 * 14 * cosh(arg) is computed from the exponential function for 15 * all arguments. 16 */ 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 = 0; 33 if(arg < 0) { 34 arg = -arg; 35 sign++; 36 } 37 if(arg > 21) { 38 temp = exp(arg)/2; 39 goto out; 40 } 41 if(arg > 0.5) { 42 temp = (exp(arg) - exp(-arg))/2; 43 goto out; 44 } 45 argsq = arg*arg; 46 temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg; 47 temp /= (((argsq+q2)*argsq+q1)*argsq+q0); 48 out: 49 if(sign) 50 temp = -temp; 51 return temp; 52 } 53 54 double cosh(double arg)55cosh(double arg) 56 { 57 if(arg < 0) 58 arg = - arg; 59 if(arg > 21) 60 return exp(arg)/2; 61 return (exp(arg) + exp(-arg))/2; 62 } 63