atan (<valarray>)
Operates on the elements of an input valarray, returning a valarray whose elements are equal to the principal value of the arctangent of the elements of the input valarray.
template<class Type>
valarray<Type> atan(
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 arctangent of the elements of the input valarray.
Remarks
The units of the returned elements are in radians.
The return value is a principal value between +pi/2 and –pi/2 that is consistent with the tangent value input.
Example
// valarray_atan.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 );
va1 [ 0 ] = -100;
for ( i = 1 ; i < 8 ; i++ )
va1 [ i ] = 5 * ( 0.25 * i - 1 );
va1 [ 8 ] = 100;
valarray<double> va2 ( 9 );
cout << "The initial valarray is: ";
for ( i = 0 ; i < 9 ; i++ )
cout << va1 [ i ] << " ";
cout << "." << endl;
va2 = atan ( va1 );
cout << "The arcsine of the initial valarray is:\n";
for ( i = 0 ; i < 9 ; i++ )
cout << setw(10) << va2 [ i ]
<< " radians, which is "
<< setw(11) << (180/pi) * va2 [ i ]
<< " degrees" << endl;
cout << endl;
}
The initial valarray is: -100 -3.75 -2.5 -1.25 0 1.25 2.5 3.75 100 .
The arcsine of the initial valarray is:
-1.5608 radians, which is -89.4271 degrees
-1.31019 radians, which is -75.0686 degrees
-1.19029 radians, which is -68.1986 degrees
-0.896055 radians, which is -51.3402 degrees
0 radians, which is 0 degrees
0.896055 radians, which is 51.3402 degrees
1.19029 radians, which is 68.1986 degrees
1.31019 radians, which is 75.0686 degrees
1.5608 radians, which is 89.4271 degrees
Requirements
Header: <valarray>
Namespace: std