#include <iostream>
#include <valarray>
int main()
{
std::valarray<double> a(10), b(10), c(10), d(10);
a = 1.2;
b = 3.1;
c = 4.0;
d = ( 2.0 * b + a ); std::cout << "d[4] = " << d[4] << std::endl;
d = (a * 2.0 + b ); std::cout << "d[4] = " << d[4] << std::endl;
d = (a + b * 2.0 ); std::cout << "d[4] = " << d[4] << std::endl;
d = (a + 2.0* b );
std::cout << "d[4] = " << d[4] << std::endl;
d = (a + 2.0* b );
std::cout << "d[4] = " << d[4] << std::endl;
d = (a + 2.0* b );
std::cout << "d[4] = " << d[4] << std::endl;
return 0;
}