diff (Matlab function) Differences and approximate derivatives

## Matlab/Scilab equivalent

Matlab | Scilab
    diff
    diff

## Particular cases

Y = diff(X[,n])

  For this kind of use of diff (dim parameter not given), Matlab works on the first non-singleton dimension of X what Scilab does not. In this case, Scilab considers dim to be "*" so that diff threats all values of X, what Matlab does not.

Y = diff(X,n,dim)

  If dimension given by dim reaches 1 before n iterations have been done, Matlab switches to next non-singleton dimension, but Scilab does not, use mtlb_diff to get equivalent results.

When n is greater than all existing dimensions of X, Matlab returns [] what Scilab may not give for all inputs.