Hi I am trying to take a derivative of an array but am having trouble. The array is two dimensional, $x$ and $y$ directions. I would like to take a derivative along $x$ and along $y$ using central difference discretization. The array has random values of numbers, no values are NaN. I will provide a basic portion of the code below to illustrate my point (assume the array $u$ is defined and has some initial values already inputted into it)
integer :: i,j integer, parameter :: nx=10, ny=10 real, dimension(-nx:nx, -ny:ny) :: u,v,w real, parameter :: h do i=-nx,nx do j=-ny,ny v = (u(i+1,j)-u(i-1,j))/(2*h) w = (u(i,j+1)-u(i,j-1))/(2*h) end do end do
Note, assume the array $u$ is defined and filled up before I find $v$ and $w$. $v$, $w$ are supposed to be derivatives of the array $u$ along $x$ and along $y$, respectively. Is this the correct way to take a derivative of an array?