Matrices and indexing

Commas separate columns and semicolons or newlines separate rows. Rows must have equal lengths.

A = [1, 2, 3;
     4, 5, 6];
disp(size(A));      % [2, 3]
disp(A(2, 1));     % 4

A(row, column) addresses a matrix element. A(index) uses 1-based column-major order. end resolves to the active axis length or total element count.

A = [1, 2, 3; 4, 5, 6];
disp(A(end, 1));
disp(A(1, end));
A(end, end) = 99;

Bare : selects an axis. Integer ranges support start:stop and start:step:stop. Reads create independent matrices; writes require an existing target.

A = [1, 2, 3; 4, 5, 6; 7, 8, 9];
rows = A(2:end, :);
last = A(:, end);
A(1:2, end) = [30; 60];

* performs matrix multiplication while .* multiplies compatible values element by element. ./ is element-wise division. The interpreter also supports compatible 2D singleton broadcasting for addition and element-wise multiplication.