TANH(X) computes the hyperbolic tangent of X. 
Fortran 77 and later, for a complex argument Fortran 2008 or later
Elemental function
X = TANH(X) 
| X | The type shall be REALorCOMPLEX. | 
The return value has same type and kind as X. If X is complex, the imaginary part of the result is in radians. If X is REAL, the return value lies in the range - 1 \leq tanh(x) \leq 1 . 
program test_tanh real(8) :: x = 2.1_8 x = tanh(x) end program test_tanh
| Name | Argument | Return type | Standard | 
| TANH(X) | REAL(4) X | REAL(4) | Fortran 77 and later | 
| DTANH(X) | REAL(8) X | REAL(8) | Fortran 77 and later | 
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Licensed under the GNU Free Documentation License, Version 1.3.
    https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gfortran/TANH.html