The diff command computes the partial derivative of the expression a with respect to x.  The most frequent use is diff(f(x),x), which computes the derivative of the function f(x) with respect to x.

If the variable of differentiation is not specified, it will be determined automatically via findsym(f,1).

If the parameter n is specified, the nth order derivative is computed.

If the derivative cannot be expressed the diff function call itself is returned.

If f is an array, the diff(f) command computes elementwise derivatives of f.  The result, R, is formed as R[i,j] = diff(f[i,j], x, n).