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# cosh

Visual Studio .NET 2003

Operates on the elements of an input valarray, returning a valarray whose elements are equal to the hyperbolic cosine of the elements of the input valarray.

```template<class Type>
valarray<Type> cosh(
const valarray<Type>& _Left
);
```

#### Parameter

_Left
The input valarray whose elements are to be operated on by the member function.

#### Return Value

A valarray whose elements are equal to the hyperbolic cosine of the elements of the input valarray.

#### Remarks

Identities defining the hyperbolic cosine in terms of exponential function:

cosh ( z ) = ( exp ( z ) + exp ( -z ) ) / 2

#### Example

```// valarray_cosh.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>
#include <iomanip>

int main( )
{
using namespace std;
double pi = 3.14159265359;
int i;

valarray<double> va1 ( 9 );
for ( i = 0 ; i < 9 ; i++ )
va1 [ i ] =  pi * ( 0.25 * i - 1 );
valarray<double> va2 ( 9 );

cout << "The initial valarray is:\n";
for (i = 0 ; i < 9 ; i++ )
cout << setw( 10 ) << va1 [ i ]
<< "  radians, which is  "
<< setw( 5 ) << ( 180/pi ) * va1 [ i ]
<< "  degrees" << endl;
cout << endl;

va2 = cosh ( va1 );
cout << "The hyperbolic cosine of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
```

#### Output

```The initial valarray is:
-3.14159  radians, which is   -180  degrees
-2.35619  radians, which is   -135  degrees
-1.5708  radians, which is    -90  degrees
-0.785398  radians, which is    -45  degrees
0  radians, which is      0  degrees
0.785398  radians, which is     45  degrees
1.5708  radians, which is     90  degrees
2.35619  radians, which is    135  degrees
3.14159  radians, which is    180  degrees

The hyperbolic cosine of the initial valarray is:
11.592
5.32275
2.50918
1.32461
1
1.32461
2.50918
5.32275
11.592
```