Texas Instruments TI-83 Manual Book page 273

matrixA ä matrixB
Multiplying a by a or a by a returns a matrix in
matrix value value matrix
which each element of is multiplied by .
matrix value
matrix ä value
value ä matrix
L (Negation)
Negating a matrix (Ì) returns a matrix in which the sign of every
element is changed (reversed).
L matrix
TI-83 Plus Matrices 270