Use valarray + valarray to double the value for each element in valarray : valarray « valarray « C++ Tutorial

#include <iostream>
#include <valarray>
#include <cmath>
using namespace std;

int main()
{
  valarray<int> v(10);

  for(int i=0; i<10; i++)
      v[i] = i;

  cout << "Original contents: ";
  for(int i=0; i<10; i++)
    cout << v[i] << " \n\n";

  v = v + v;

  for(int i=0; i<10; i++)
    cout << v[i] << " \n\n";


  cout << endl;
}

Original contents: 0

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20.1.valarray
	20.1.1.	Create valarray of bool value by using comparison operator on another valarray
	20.1.2.	subtracting 10 from each element
	20.1.3.	Minus 10 from each element in a valarray
	20.1.4.	Plus two valarrays together
	20.1.5.	Get square root of elements in a valarray
	20.1.6.	Use valarray + valarray to double the value for each element in valarray
	20.1.7.	Do sqrt for all elements in a valarray
	20.1.8.	Print three-dimensional valarray line-by-line
	20.1.9.	Print valarray as two-dimensional array
	20.1.10.	valarray with double value inside