If an mxn matrix A has been defined, the command G = newhat(A) defines an (m + n)x(m + n) matrix G that is the matrix called A hat (that is, A with a circumflex accent over it) on page 19. The upper left mxn corner of G is A, the upper right mxm corner is an identity matrix, the lower left nxn corner is an identity matrix, and the lower right nxm corner is a matrix of zeros, except that the very last entry in the bottom right corner is the number m of rows in A. This number is put there for later use by the `unhat' function. (Note that the row and column operations that are to be applied to G affect only the first m rows and the first n columns and will leave this special last entry unchanged.)
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