An expression involving the multiplication of Vectors and/or Matrices (possibly and/or Arrays) has been constructed using the standard multiplication operator, `*`, which is ambiguous.

Note that in 2-D math `*` displays as a center dot: `⋅`, and typing a dot (using the period key) displays as `$·$`, as show in the following table.

This display can be modified through the interactive Typesetting Rule Assistant.

For Vector/Matrix multiplication, use . (dot).  If instead you want to perform elementwise multiplication, use *~.

 Example 1:

This error results if Matrices, or a Matrix and a Vector, are multiplied using a commutative multiplication operator, `*`:

Solution 1:

To multiply Matrices and/or Vectors together using the standard Linear Algebra multiplication operation, use the non-commutative multiplication operator, `.` (dot):

Example 2:

Implicit multiplication (using a space to mean multiplication) can also be ambiguous.

Solution 2:

To multiply Vectors and/or Matrices and/or Arrays together using elementwise multiplication, use the standard multiplication operator, `*` followed by the "elementwise" operator, `~`:

Note that when multiplying Arrays together (not with Vectors or Matrices), the standard multiplication operator will result in the elementwise product, so the `~` is not necessary:

Note also that implicit multiplication is interpreted based on the operands, and when it can, Maple parses these as follows: For Vector/Matrix operands this will be interpreted as the `.` (dot) non-commutative multiplication operator, while for Array operands this will be interpreted as the elementwise operator:

However, best practice is to insert the explicit multiplication operator into your expressions.