Trailing-Edge
-
PDP-10 Archives
-
SRI_NIC_PERM_FS_1_19910112
-
kcc-6/lib/math/tanh.c
There are 7 other files named tanh.c in the archive. Click here to see a list.
/*
* +++ NAME +++
*
* TANH Double precision hyperbolic tangent
*
* +++ INDEX +++
*
* TANH
* machine independent routines
* math libraries
*
* +++ DESCRIPTION +++
*
* Returns double precision hyperbolic tangent of double precision
* floating point number.
*
* +++ USAGE +++
*
* double tanh(x)
* double x;
*
* +++ REFERENCES +++
*
* Fortran IV plus user's guide, Digital Equipment Corp. pp B-5
*
* +++ RESTRICTIONS +++
*
* For precision information refer to documentation of the
* floating point library routines called.
*
* +++ PROGRAMMER +++
*
* Fred Fish
* Goodyear Aerospace Corp, Arizona Div.
* (602) 932-7000 work
* (602) 894-6881 home
*
* Modifications for inclusion in standard C library are
* (c) Copyright Ian Macky, SRI International 1985
* Additional modifications after v.4, 2-Jul-1986 are
* (c) Copyright Ken Harrenstien 1989
*
* This routine now conforms with the description of the tanh()
* function as defined in
* Harbison & Steele's "C: A Reference Manual", section 11.3.26
*
* +++ INTERNALS +++
*
* Computes hyperbolic tangent from:
*
* tanh(X) = 1.0 for X > TANH_MAXARG
* = -1.0 for X < -TANH_MAXARG
* = sinh(X) / cosh(X) otherwise
*
* ---
*/
#include <math.h>
#include <errno.h>
#include "pml.h"
double tanh(x)
double x;
{
if (x > TANH_MAXARG)
return 1.0;
if (x < -TANH_MAXARG)
return -1.0;
return sinh(x) / cosh(x);
}