# cosh

This function computes the hyperbolic cos of a number.

# COSH

## NAME

cosh - This function computes the hyperbolic cos of a number.

cosh(number)

## DESCRIPTION

This mathematical function allows the user to compute the hyperbolic cos of an argument defined between -infinity to infinity. This is not a periodic function, unlike its basis function: the cos function. It returns a value only in the 1st or the 2nd quadrant of the xy plane, meaning that if x<0, y>0, and if x>0, y>0. The cosh function is defined as cosh x = 0.5 * ( exp(x) exp(-x)), and cosh(x)=cos(ix).

## PARAMETERS

number
Specify the number (float) used as argument for the cosh function.

## RETURN

Cosh
The cosh value of the argument.

## EXAMPLES

Note: In the followings examples, the _ between the { should be removed to make it work.

```One can use this function with positive integers:

test(q(res={_{cosh(1);}}.),q(res=1.54308.));

With negative integers:

test(q(res={_{cosh(-1);}}.),q(res=1.54308.));

Note that cosh(-x)=cosh(x).

With big integers:

test(q(res={_{cosh(45);}}.),q(res=1.74671e+19.));

Note that the answer is a monstrous number. Since it is a hyperbolic function,
it goes to infinity really fast until cosh(inf)=inf.

With other variables:

test(q(res={_{
%include "/includes/extenso.sn";
a=PI;
cosh(a);
}}.),
q(res=11.592.));

With another trigonometric function:

test(q(res={_{
%include "/includes/extenso.sn";
a=sin(0);
cosh(a);
}}.),
q(res=1.));

With an array:

test(q(res={_{cosh(1,0,-1);}}.),q(res=\[1.54308,1,1.54308\].));
```