Changes

__global__ void Calculate (float* u, float* un,int nx, int c, float dx, float dt)

{

int j = blockIdx.x * blockDim.x + threadIdx.x;

int i = blockIdx.y * blockDim.y + threadIdx.y;

// removes from instructions because no need to do this NX amount of times

float total = c*dt / dx;

if (i < nx && j < nx)

{

for (int it = 1; it <= nx- 1; it++)

{