I would like the shortest code to build the following matrices, of arbitrary dimension $N$:
A Low-Pass filter bank matrix is of the form
$ \begin{bmatrix} 1 & 1 & 0 & 0 & \dots & 0 & 0 & 0 \\ & 1 & 1 & 0 & \dots & 0 & 0 & 0 \\ & &1 & 1 & \dots & 0 & 0 & 0 \\ & & & & \ddots & \vdots & \vdots & \vdots \\ & & & & \dots & 1 & 1 & 0 \\ & & & & \dots & & 1 & 1 \\ & & & & \dots & & & 1 \end{bmatrix} _{N\times N} $
A High-Pass filter bank matrix is of the form:
$ \begin{bmatrix} 1 & -1 & 0 & 0 & \dots & 0 & 0 & 0 \\ & 1 & -1 & 0 & \dots & 0 & 0 & 0 \\ & &1 & -1 & \dots & 0 & 0 & 0 \\ & & & & \ddots & \vdots & \vdots & \vdots \\ & & & & \dots & 1 & -1 & 0 \\ & & & & \dots & & 1 & -1 \\ & & & & \dots & & & 1 \end{bmatrix} _{N\times N} $
How can I build the above matrices for any dimension $N$?