diff

Purpose

Differences and approximate derivatives.

Synopsis

y = diff(x)
y = diff(x,n)

Description

diff calculates differences. If x is a row or column vector

x = [x(1) x(2) ... x(n)]
then y = diff(x) returns a vector of differences between adjacent elements

[x(2)-x(1)  x(3)-x(2)... x(n)-x(n-1)]
The output vector is one element shorter than the input vector. If x is a matrix, the differences are calculated down each column:

diff(X) = X(2:m,:)-X(1:m-1,:)
y = diff(x,n) is the n-th difference function:

diff(x,n) = diff(diff(x,n-1))

Examples

diff(y)./diff(x) is an approximate derivative.

See Also

de12, prod, sum

(c) Copyright 1994 by The MathWorks, Inc.