Texas Instruments TI-83 PLUS - Manual (Page 274)

TI-83 Plus Matrices 271
abs(
abs( (absolute value,
MATH NUM
menu) returns a matrix containing the
absolute value of each element of matrix .
abs( matrix )
round(
round( (
MATH NUM
menu) returns a matrix. It rounds every element in
matrix to # decimals (  9). If #decimals is omitted, the elements are rounded
to 10 digits.
round( matrix [ , #decimals ] )
M 1 (Inverse)
Use the L 1 function ( œ ) to invert a matrix ( ^ L 1 is not valid). matrix must be
square. The determinant cannot equal zero.