How can I solve it: Matrix dimensions must agree.

function A = matrixCSums(M)
% M is a numeric matrix and A has the same size as M.
% Each element in A is the sum of the corresponding element in M and all
% the elements above it.  Example:
%   M = [ 1 3; ...             A = [ 1  3; ...
%         4 5; ...                   5  8; ...
%        -7 2]         then         -2 10]
% Do NOT use any built-in functions other than size
if M ==[]
    A=[];
else
    A(1,:)=M(1,:); %initial row of A
    [nr,nc]=size(M);
    for i=2:nr
    A(i,:)=A(i-1,:)+M(i,:);
    end
end

When I call the function:

M = [ 1 3; 4 5; -7 2];
A = matrixCSums(M)

it says:

Error using ==

Matrix dimensions must agree.

Error in matrixCSums (line 9)

if M ==[]

Answer 1

[Alan Stevens]

Replace

if M ==[]

with

  if isempty(M)

Answer 2

[drummer]

if M == []
    A(M == []) = [];
else
    % rest of your code here.
end

Hope that helps.

Cheers

[Walter Roberson]

M == [] is going to fail unless M is empty (but will work if M is a different size of empty).