Texas Instruments TI-83 PLUS - Manual (Page 273)

TI-83 Plus Matrices 270
matrixA ä matrixB
Multiplying a matrix by a value or a value by a matrix returns a matrix in
which each element of matrix is multiplied by 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