<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">
Suppose I have two sparse matrices A and Q and now I want to construct a block diagonal matrix, K,<div><br></div><div>K = <span class="Apple-tab-span" style="white-space:pre"> </span>[A,0]</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>[0,Q]<br class="webkit-block-placeholder"></div><div><br class="webkit-block-placeholder"></div><div>What is the "right" way to do this is?</div><br><br><div> <span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">-Gideon Simpson</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> Department of Applied Physics and Applied Mathematics</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> Columbia University</div><br class="Apple-interchange-newline"></span> </div><br></body></html>