Subscripted assignment dimension mismatch in MCMV code

Question

The below code gives me a error:

Subscripted assignment dimension mismatch.

Error in ==> lookmcvmt at 18

M(:,:,j,i) = mcmvOUT2((k+1):(k+Nz), i:Nt:Nr);

Please help to solve.

load MCMVout1xzy
mcmvOUT2 = MCMVout1xzy;
whos
[Nr2 Nr] = size(mcmvOUT2);
Ny = 51;
Nx = 51;
Nz = 41;
Nt = 10;
M = zeros(Nz,Nx,Ny,Nt);
for j=1:Ny
    for i=1:Nt
        k = Nz*(j-1);
        M(:,:,j,i) = mcmvOUT2((k+1):(k+Nz), i:Nt:Nr);
    end
end

xenoclast xenoclast · Accepted Answer · 2015-05-19T13:12:57

The error 'subscripted assignment dimension mismatch' means you are trying to assign a block of values into a space that is the wrong size.

This entity

mcmvOUT2((k+1):(k+Nz), i:Nt:Nr);

represents a matrix of values in 2 dimensions. Its size is defined by the two ranges specified by (k+1):(k+Nz) and i:Nt:Nr - you can check its size by typing

size(mcmvOUT2((k+1):(k+Nz), i:Nt:Nr))

The space you are trying to fit it into has to be exactly the same dimensions. The size of the range specified by

M(:,:,j,i)

is defined by the Nz and Nx arguments to the zeros call with which you preallocated the array.

We can't test this because the MCMVout1xzy file containing your data is not given, but you will be able to solve this yourself by using the size command and making sure all your dimensions match.

Because matlab uses column-wise indexing, and a lot of us are used to the row-wise paradigm of cartesian coordinate systems, getting the order of your indexes right can be confusing - this is the root of a lot of these kinds of error (for me anyway).

Things to check: your dimensions Nz etc. are correct and the order of your Nz etc. variables in the zeros call is correct.

Subscripted assignment dimension mismatch in MCMV code

1 Answers