/C

# tanh, tanhf, tanhl

Defined in header `<math.h>`
`float       tanhf( float arg );`
(1) (since C99)
`double      tanh( double arg );`
(2)
`long double tanhl( long double arg );`
(3) (since C99)
Defined in header `<tgmath.h>`
`#define tanh( arg )`
(4) (since C99)
1-3) Computes the hyperbolic tangent of `arg`.
4) Type-generic macro: If the argument has type `long double`, `tanhl` is called. Otherwise, if the argument has integer type or the type `double`, `tanh` is called. Otherwise, `tanhf` is called. If the argument is complex, then the macro invokes the corresponding complex function (`ctanhf`, `ctanh`, `ctanhl`).

### Parameters

 arg - floating point value representing a hyperbolic angle

### Return value

If no errors occur, the hyperbolic tangent of `arg` (tanh(arg), or
 earg-e-arg earg+e-arg
) is returned.

If a range error occurs due to underflow, the correct result (after rounding) is returned.

### Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

• if the argument is ±0, ±0 is returned
• If the argument is ±∞, ±1 is returned
• if the argument is NaN, NaN is returned

### Notes

POSIX specifies that in case of underflow, `arg` is returned unmodified, and if that is not supported, an implementation-defined value no greater than DBL_MIN, FLT_MIN, and LDBL_MIN is returned.

### Example

```#include <stdio.h>
#include <math.h>

int main(void)
{
printf("tanh(1) = %f\ntanh(-1) = %f\n", tanh(1), tanh(-1));
printf("tanh(0.1)*sinh(0.2)-cosh(0.2) = %f\n", tanh(0.1) * sinh(0.2) - cosh(0.2));
// special values
printf("tanh(+0) = %f\ntanh(-0) = %f\n", tanh(0.0), tanh(-0.0));
}```

Output:

```tanh(1) = 0.761594
tanh(-1) = -0.761594
tanh(0.1)*sinh(0.2)-cosh(0.2) = -1.000000
tanh(+0) = 0.000000
tanh(-0) = -0.000000```

### References

• C11 standard (ISO/IEC 9899:2011):
• 7.12.5.6 The tanh functions (p: 242)
• 7.25 Type-generic math <tgmath.h> (p: 373-375)
• F.10.2.6 The tanh functions (p: 520)
• C99 standard (ISO/IEC 9899:1999):
• 7.12.5.6 The tanh functions (p: 222-223)
• 7.22 Type-generic math <tgmath.h> (p: 335-337)
• F.9.2.6 The tanh functions (p: 457)
• C89/C90 standard (ISO/IEC 9899:1990):
• 4.5.3.3 The tanh function

 sinhsinhfsinhl (C99)(C99) computes hyperbolic sine (sh(x)) (function) coshcoshfcoshl (C99)(C99) computes hyperbolic cosine (ch(x)) (function) atanhatanhfatanhl (C99)(C99)(C99) computes inverse hyperbolic tangent (artanh(x)) (function) ctanhctanhfctanhl (C99)(C99)(C99) computes the complex hyperbolic tangent (function) C++ documentation for `tanh`