diffCenter

% dx = diffCenter(x,dt)
%
% Computes the second-order finite difference approximation of x with
% respect to t. A one-sided second order difference is used at the end
% points, so size(dx) == size(x).
%
% INPUTS:
% x = [m, n] = matrix of function values over a uniform time grid n
% dt = sampling period of x (default = 1)
%
% OUTPUTS:
% d = dx/dt = first derivative of x wrt t
%
% NOTES:
% This command is very similar to Matlab's gradient command. The
% difference between the two is how they handle the boundaries.
% DiffCenter (this function) uses a second-order finite difference,
% while gradient (by Matlab) uses a first-order finite difference.
% The functions are identical for interior points.
%
% See also: cumInt, diff, gradient
%