Error: Matrix dimensions must agree

I am trying to execute this piece of code but cannot figure out why I am getting this error, any help is much appriciated.

yp=kron(eye(32),[-1/.5 0;1 0]).*ones(2*32,1)+80*pi.*kron(ones(32),1);[1/.5;0]+2.*90.*diag(ones(2*32-1,1),1).*(kron(ones(32,1),[;1/.5])).*cos(zeros(2*32-1,1)).*(sin(8.*((1/64):(1/64):10)-ones(2*32,1)))./.5

Answer 1

[Jan]

Seriously? Your code contains some jokes:

• -1/.5 == 2
• kron(eye(32), [-2, 0; 1, 0]) .* ones(64, 1) == kron(eye(32), [-2, 0; 1, 0])
• kron(ones(32), 1) == ones(32)

So a simplified version of the first line is:

yp = kron(eye(32), [-2, 0; 1, 0]) + 80 * pi * ones(32);
%    [64 x 64]                    + [32 x 32]

This cannot work. If you really want to add this, omit the expanding of the 2nd term to a matrix:

yp = kron(eye(32), [-2, 0; 1, 0]) + 80 * pi;

The 2nd part ise useless at all, even if it would work, because the result is not assigned to a variable. So the best solution is simply to delete the 2nd line. By the way, this line contains invalid Matlab syntax:

[1/.5 ; 0] + 2 .* 90 .* diag(ones(63, 1), 1) .* ...
(kron(ones(32, 1), [;1/.5])) .* ...
...     %          ^ what should this be?!?
cos(zeros(63, 1)) .* sin(8 .* ((1/64):(1/64):10) - ones(64, 1)) ./ .5
% [63 x 1]        .* [64 x 640]   : cannot match

Expressions like cos(zeros(2*32-1,1)) are a waste of time, because cos(0)==1, so this replace this by ones(63,1).

But as said already: because this part of the code does not perform anything useless, it is easier to delete it than to fix it.

I cannot image a serious task, in which such code could appear.

[bl276]

Thanks Jan,

The code comes from a published book. I also could not see how this code could work as is. I did make a typo when eliminating the variables ( [0:1/.5] is what it should read). The code is intened to model pattern formation in the hippocampus.

Here is a snapshot of the code from the book if you are intrigued:

(The part I attempted to shows is at the bottom, this is where I got the matrix error)