BSD 4_3 release

[unix-history] / usr / src / usr.lib / libom / sinh.c

/*      @(#)sinh.c      4.1     12/25/82        */

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

       The exponential function is called for arguments
       greater in magnitude than 0.5.

       A series is used for arguments smaller in magnitude than 0.5.
       The coefficients 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;

double
sinh(arg)
double arg;
{
       double temp, argsq;
       register sign;

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

       if(arg > 21.) {
               temp = exp(arg)/2;
               if (sign>0)
                       return(temp);
               else
                       return(-temp);
       }

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

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

double
cosh(arg)
double arg;
{
       if(arg < 0)
               arg = - arg;
       if(arg > 21.) {
               return(exp(arg)/2);
       }

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