NAME

tanh(), tanhf() − hyperbolic tangent functions

SYNOPSIS

#include <math.h>

double tanh(double x);

float tanhf(float x);

DESCRIPTION

The tanh() function returns the hyperbolic tangent of its argument. 

tanhf() is a float version of tanh(); it takes a float argument and returns a float result.  To use this function, compile either with the −Ae option or with the −Aa and −D_HPUX_SOURCE options.  Otherwise, the compiler promotes the float argument to double, and the function returns incorrect results. 

tanhf() is not specified by any standard, but it is named in accordance with the conventions specified in the "Future Library Directions" section of the ANSI C standard. 

To use these functions, link in the math library by specifying −lm on the compiler or linker command line. 

RETURN VALUE

If x is ±INFINITY, tanh() returns ±1.0 respectively. 

If x is NaN, tanh() returns NaN. 

If the correct value after rounding would be smaller in magnitude than MINDOUBLE, tanh() returns zero. 

ERRORS

No errors are defined. 

SEE ALSO

sinh(3M), cosh(3M), isinf(3M), isnan(3M), values(5). 

STANDARDS CONFORMANCE

tanh(): SVID3, XPG4.2, ANSI C

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996