what is matrix3d?

my code is neighbors = matrix3d(i-1:i+1, j-1:j+1, k-1:k+1);

It gives error like,

Undefined function or variable 'matrix3d'.

Answer 1

[KSSV]

matrix3D is the variable 3D matrix you have. You have not defined it.

matrix3d = rand(10,10,10) ;
% say i = 1, j = 1
i = 2 ; j=3, k = 2
neighbors = matrix3d(i-1:i+1, j-1:j+1, k-1:k+1)

[Walter Roberson]

Right. This appears to refer back to https://www.mathworks.com/matlabcentral/answers/310452-how-can-i-find-26-neighbors-of-point-with-coordinates-of-i-j-k#answer_241820 where matrix3d was simply the name of the variable that Image Analyst used to represent the your 3D data set.

[Walter Roberson]

And see https://www.mathworks.com/matlabcentral/answers/310452-how-can-i-find-26-neighbors-of-point-with-coordinates-of-i-j-k#answer_258769