ijacobian
Jacobian of a multivariate, vectorvalued function using the complexstep approximation.
Back to Numerical Differentiation Toolbox Contents.
Contents
Syntax
J = ijacobian(f,x0) J = ijacobian(f,x0,h)
Description
J = ijacobian(f,x0) numerically evaluates the Jacobian of with respect to at using the complexstep approximation with a default step size of .
J = ijacobian(f,x0,h) numerically evaluates the Jacobian of with respect to at using the complexstep approximation with a userspecified step size .
Input/Output Parameters
Variable  Symbol  Description  Format  
Input  f  multivariate, vectorvalued function ()  1×1 function_handle 

x0  evaluation point  n×1 double 

h  (OPTIONAL) step size  1×1 double 

Output  J  Jacobian of with respect to , evaluated at  m×n double 
Note
 This function requires evaluations of .
Example
Approximate the Jacobian of
at using the ijacobian function, and compare the result to the true result of
Approximating the Jacobian,
f = @(x) [x(1);5*x(3);4*x(2)^22*x(3);x(3)*sin(x(1))]; x0 = [5;6;7]; J = ijacobian(f,x0)
J = 1.0000 0 0 0 0 5.0000 0 48.0000 2.0000 1.9856 0 0.9589
Calculating the error,
error = J[1,0,0;0,0,5;0,48,02;7*cos(5),0,sin(5)]
error = 0 0 0 0 0 0 0 0 0 0 0 0
NOTE: The function and its corresponding Jacobian are from an example on Wikipedia.