Bell 32V development

[unix-history] / usr / src / libF77 / sinh.c

/*
       sinh(arg) returns the hyperbolic sign of its floating-
       point argument.

       The exponential function is called for arguments
       greater in magnitude than 0.5.
       The result overflows and 'huge' is returned for
       arguments greater than somewhat.

       A series is used for arguments smaller in magnitude than 0.5.
       The coeffieients are #2029 from Hart & Cheney. (20.36D)

       cosh(arg) is computed from the exponential function for
       all arguments.
*/

double exp();

static double p0 -0.6307673640497716991184787251e+6;
static double p1 -0.8991272022039509355398013511e+5;
static double p2 -0.2894211355989563807284660366e+4;
static double p3 -0.2630563213397497062819489e+2;
static double q0 -0.6307673640497716991212077277e+6;
static double q1  0.1521517378790019070696485176e+5;
static double q2 -0.173678953558233699533450911e+3;
static double q3  1.0;

double
sinh(arg) double arg; {

       double sign, temp, argsq;

       sign = 1;
       if(arg < 0){
               arg = - arg;
               sign = -1;
       }

       if(arg > 21.){
               temp = exp(arg)/2;
               return(sign*temp);
       }

       if(arg > 0.5) {
               temp = (exp(arg) - exp(-arg))/2;
               return(sign*temp);
       }

       argsq = arg*arg;
       temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg;
       temp = temp/(((q3*argsq+q2)*argsq+q1)*argsq+q0);
       return(sign*temp);

}

double
cosh(arg) double arg; {

       double temp;

       if(arg < 0)
               arg = - arg;

       if(arg > 21.){
               temp = exp(arg)/2;
               return(temp);
       }

       temp = (exp(arg) + exp(-arg))/2;
       return(temp);
}