void resize( std::size_t count, T value = T() );      
Resizes the valarray to contain count elements and assigns value to each element.
This functions invalidates all pointers and references to elements in the array.
  Parameters 
 count   -   new size of the container   value   -   the value to initialize the new elements with  
  Return value 
(none).
  Example 
  #include <valarray>
#include <iostream>
int main()
{
    std::valarray<int> v{1,2,3};
    v.resize(10);