Get the 2nd derivatives of a vector with two finite boundaries

The function gets the 2nd derivatives of a vector with two finite boundaries

The function gets the 2nd derivatives of a vector with two finite boundaries.

function V2ndDx = get_V2ndDx(V,delta_x,INDstart,INDend)

Input:
V = the input vector, 1D data
delta_x = delta x
INDstart = first index
INDend = last index

Output:
V2ndDx = 2nd derivative of M with respect to x (horizontal direction)