Why can't I multiply two arrays using the '*' operator?

Why is it necessary to use the .* operator to multiply two arrays of the same size? For example, if I have array1 = [1,2,3] and array2 [4,5,6] which both have size of 3; why is it not possible to simply use '*'?

Answer 1

[Star Strider]

Because the dot operator does element-wise multiplication (and division and exponentiation). These are termed array operations in MATLAB.

If you do not use the dot operator, you are using standard linear algebra matrix operations, and those require that you follow the rules for array operations from linear algebra.

array1 = [1,2,3];
array2 = [4,5,6];

Result1 = array1' * array2;         % 3x3 Matrix (Matrix Multiplication)
Result2 = array1 * array2';         % Scalar (Dot Product)
Result3 = array1 .* array2;         % 1x3 (Element-Wise Multiplication)

See the documentation on Array vs. Matrix Operations (link) for details.