Legacy Document

cosh

You can use the cosh function to compute the hyperbolic cosine of a real number.

double_t cosh (double_t x);

x

Any floating-point number.

DESCRIPTION

The cosh function returns the hyperbolic cosine of its argument. This function is symmetric.

The acosh function performs the inverse operation $(arccosh(y))$ .

EXCEPTIONS

When x is finite and nonzero, the result of $cosh(x)$ might raise one of the following exceptions:

• inexact (for all finite, nonzero values of x)
• overflow (if the result is outside the range of the data type)

SPECIAL CASES

Table 10-27 shows the results when the argument to the cosh function is a zero, a NaN, or an Infinity.

Special cases for the cosh function

Operation	Result	Exceptions raised
$cosh(+0)$	+1	None
$cosh(-0)$	+1	None
$cosh(NaN)$	NaN	None[49]
$cosh(+$ )	+	None
$cosh(-$ )	+	None

EXAMPLES

z = cosh(1.0);    /* z  1.54308. The inexact exception is 
                     raised. */
z = cosh(-1.0);   /* z  1.54308. The inexact exception is 
                     raised. */

---

[49] If the NaN is a signaling NaN, the invalid exception is raised.