#include <iostream>
using namespace std;

// Take a time step for the heat equation u_t = D u_{xx} using the 3 point explicit
// forward Euler method.  This amounts to

//               uNew[i] = a * uOld[i-1] + b*uOld[i] + c * uOld[i+1]

int TimeStep( double* uNew, double* uOld, double dx, double dt, double D, int nu ){

	double a = D*dt/(dx*dx);
	double c = D*dt/(dx*dx);
	double b = 1 - 2*D*dt/(dx*dx);

	int maxu = nu-1;
	for (int i = 1; i < maxu; i++ )

		uNew[i] = a * uOld[i-1] + b*uOld[i] + c * uOld[i+1];

	return 0;
}