Brackets around blkarray are too big

This is a followup to this question.

MWE (given by Henri Menke in the linked post):

\documentclass{article}
\usepackage{blkarray}
\begin{document}
$\left[ \begin{blockarray}{ccccccc} \begin{block}{[ccc]cccc} I_p \\ & \ddots \\ & & I_p \\ \end{block} \begin{block}{c[ccc]ccc} & I_p \\ & & \ddots \\ & & & I_p \\ \end{block} & & & \vdots & \ddots \\ & & & \ddots & \vdots \\ \begin{block}{cccc[ccc]} & & & & I_p \\ & & & & & \ddots \\ & & & & & & I_p \\ \end{block} \end{blockarray} \right]$
\end{document}


This produces this:

This is almost what I want, except the brackets produced by \left[ and \right are too long on the bottom. I feel like there must be a way to do this exclusively in a blockarray, but the documentation for the package is not extensive enough that it has quickly led me to such a solution.

blkarray is so weird....
\documentclass{article}
\left[ \begin{blockarray}{ccccccc} \begin{block}{[ccc]cccc} I_p \\ & \ddots \\ & & I_p \\ \end{block} \begin{block}{c[ccc]ccc} & I_p \\ & & \ddots \\ & & & I_p \\ \end{block} & & & \vdots & \ddots \\ & & & \ddots & \vdots \\ \begin{block}{cccc[ccc]} & & & & I_p \\ & & & & & \ddots \\ & & & & & & I_p \\ \end{block} \end{blockarray} \right] + \left[ \begin{blockarray}{ccccccc} \begin{block}{[ccc]cccc} I_p \\ & \ddots \\ & & I_p \\ \end{block} \begin{block}{c[ccc]ccc} & I_p \\ & & \ddots \\ & & & I_p \\ \end{block} & & & \vdots & \ddots \\ & & & \ddots & \vdots \\ \begin{block}{cccc[ccc]} & & & & I_p \\ & & & & & \ddots \\ & & & & & & I_p \\ \end{block} \BAnoalign{\vspace{-20pt}} \end{blockarray} \right]

• You should contact the author of blkarray about this. ;) – Henri Menke Feb 22 at 23:19