The matrix expression must be specified first on
the MSAVE statement.
The matrix expression specification can be any matrix
language expression that evaluates to the value(s) to be written to
the matrix-format file.
You can specify a matrix name, a matrix raised to
a power, or a matrix function (with its arguments in parentheses)
by itself, but you must enclose other matrix expressions in parentheses.
For example, MSAVE A, SAVE INV(A), or MSAVE B**DET(T(C)*D) is legal, but MSAVE N * WT is not. You must specify MSAVE (N * WT).