diff

Arguments

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/matrix

Description

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

diff(x,n,dim) is the nth 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)

See also

• interp — cubic spline evaluation function
• interp2d — bicubic spline (2d) evaluation function
• splin — cubic spline interpolation
• eval_cshep2d — bidimensional cubic shepard interpolation evaluation
• numderivative — approximation des dérivées d'une fonction (matrices jacobienne ou hessienne)
• sgolaydiff — Numerical derivatives computation using Savitzky-Golay filter.