# cos (<valarray>)

Visual Studio 2013

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

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

## Parameters

_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 absolute value of the elements of the input valarray.

## Example

```// valarray_cos.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 = cos ( va1 );
cout << "The cosine of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << va2 [ i ] << endl;
}
```
```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 cosine of the initial valarray is:
-1
-0.707107
-1.03412e-013
0.707107
1
0.707107
-1.03412e-013
-0.707107
-1```