Restricting random matrices

[DrD]

(03-19-2014 05:29 PM)Helge Gabert Wrote:  One example of a Toeplitz matrix would be:

MAKEMAT(J-I, n, n) or some variation thereof. Caution: This seems to only work in Home.

For the general case, you'll have to create your vectors which you would like to propagate along the minor diagonals and write a short PPL program.

Thanks for putting me onto these interesting results:
With n>0,
MAKEMAT(J-I,n,n) produces a symmetric matrix left leaning.
MAKEMAT(J+I,n,n) produces a symmetric matrix right leaning.
MAKEMAT(J==I,n,n) produces the identity matrix.
MAKEMAT(J==I^-1,n,n) produces a symmetric matrix with 1's on the main diagonal, and +/- infinity otherwise.

Other operators on J and I produce interesting results, as well.