Symmetric Toeplitz Array

[sbev]

I need to create numerous symmetric Toeplitz matrices from different beginning 1-dimensional arrays. It is straight forward to do with DO loops, but want to know if it can be done efficiently with intrinsic functions in 90/95. The problem is:

Given n numbers, x1, x2, ..., xn, form an n by n array x such that x(1,1:n) = x1, ..., xn; x(i,i) = x1; and x(i,j) = x(j,i).

 

[salgerman]

I just had to google Toeplitz matrices, never heard of it.

If you put your x1,...,xn numbers into a single one-dimensional array, xs, I think you can do it in a single loop:

do i = 1,n
   toe(i,i:n) = xs(1:(n+1-i))
   toe(i:n,i) = xs(1:(n+1-i))
end do

Is this acceptable?

 

[sbev]

Thanks salgerman, the solution works great.