The MAT statement lets you implicitly create  and  manipulate  one-  and
  two-dimensional  arrays.  You can use the MAT statement to assign values
  to array elements, or to redimension  a  previously  dimensioned  array.
  You   can   also   perform   matrix   arithmetic   operations   such  as
  multiplication, addition, and subtraction, and other  matrix  operations
  such as transposing and inverting matrices.

  Examples:

  MAT First_array = ZER
  MAT String_array = NUL$
  MAT A = B + C
  MAT C = (55.2) * First_array