## Name

diff — Difference and discrete derivative

## Calling Sequence

y=diff(x)
y=diff(x [,n [,dim]])

## Parameters

- x
vector or matrix (real, complex, sparse or polynomial)

- n
integer the order of differentiation

- dim
integer or character string with values "r","c" and "*"

- y
scalar or vector

## Description

`y=diff(x)`

compute the difference function
y=x(2:$)-x(1:$-1)

`diff(x,n,dim)`

is the `n`

th
difference function along dimension `dim`

.

`diff(x,n,"*")`

is equivalent to
diff(x(:),n).

Default value for `n`

is 1. Default value for
`dim`

is `"*"`

.

`dim='r'`

is equivalent to `dim=1`

and `dim='c'`

is equivalent to
`dim=2`

.

## Examples

v=(1:8)^3;
diff(v)
diff(v,3)
A=[(1:8)^2
(1:8)^3
(1:8)^4];
diff(A,3,2)
//approximate differentiation
step=0.001
t=0:step:10;
y=sin(t);
dy=diff(sin(t))/step; //approximate differentiation of sine function
norm(dy-cos(t(1:$-1)),%inf)