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Annotation of 42BSD/usr.lib/libF77/sinh.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  *     "@(#)sinh.c     1.1"
                      3:  */
                      4: 
                      5: /*
                      6:        sinh(arg) returns the hyperbolic sine of its floating-
                      7:        point argument.
                      8: 
                      9:        The exponential function is called for arguments
                     10:        greater in magnitude than 0.5.
                     11: 
                     12:        A series is used for arguments smaller in magnitude than 0.5.
                     13:        The coefficients are #2029 from Hart & Cheney. (20.36D)
                     14: 
                     15:        cosh(arg) is computed from the exponential function for
                     16:        all arguments.
                     17: */
                     18: 
                     19: double exp();
                     20: 
                     21: static double p0  = -0.6307673640497716991184787251e+6;
                     22: static double p1  = -0.8991272022039509355398013511e+5;
                     23: static double p2  = -0.2894211355989563807284660366e+4;
                     24: static double p3  = -0.2630563213397497062819489e+2;
                     25: static double q0  = -0.6307673640497716991212077277e+6;
                     26: static double q1   = 0.1521517378790019070696485176e+5;
                     27: static double q2  = -0.173678953558233699533450911e+3;
                     28: 
                     29: double
                     30: sinh(arg)
                     31: double arg;
                     32: {
                     33:        double temp, argsq;
                     34:        register sign;
                     35: 
                     36:        sign = 1;
                     37:        if(arg < 0) {
                     38:                arg = - arg;
                     39:                sign = -1;
                     40:        }
                     41: 
                     42:        if(arg > 21.) {
                     43:                temp = exp(arg)/2;
                     44:                if (sign>0)
                     45:                        return(temp);
                     46:                else
                     47:                        return(-temp);
                     48:        }
                     49: 
                     50:        if(arg > 0.5) {
                     51:                return(sign*(exp(arg) - exp(-arg))/2);
                     52:        }
                     53: 
                     54:        argsq = arg*arg;
                     55:        temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg;
                     56:        temp /= (((argsq+q2)*argsq+q1)*argsq+q0);
                     57:        return(sign*temp);
                     58: }
                     59: 
                     60: double
                     61: cosh(arg)
                     62: double arg;
                     63: {
                     64:        if(arg < 0)
                     65:                arg = - arg;
                     66:        if(arg > 21.) {
                     67:                return(exp(arg)/2);
                     68:        }
                     69: 
                     70:        return((exp(arg) + exp(-arg))/2);
                     71: }

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