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9 | | - <title>1. Preliminaries — Computational linear algebra course 2020.0 documentation</title> |
| 9 | + <title>1. Preliminaries — Computational linear algebra course 2022.0 documentation</title> |
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@@ -57,7 +57,8 @@ <h1><span class="section-number">1. </span>Preliminaries<a class="headerlink" hr |
57 | 57 | <div class="admonition hint"> |
58 | 58 | <p class="admonition-title">Hint</p> |
59 | 59 | <p>Before you attempt any exercises, you need to make sure that you |
60 | | -have everything you need set up on your computer.</p> |
| 60 | +have everything you need set up on your computer. See the checklist |
| 61 | +in <a class="reference internal" href="exercises.html#comp-exercises"><span class="std std-ref">the exercises section</span></a>.</p> |
61 | 62 | </div> |
62 | 63 | <section id="matrices-vectors-and-matrix-vector-multiplication"> |
63 | 64 | <h2><span class="section-number">1.1. </span>Matrices, vectors and matrix-vector multiplication<a class="headerlink" href="#matrices-vectors-and-matrix-vector-multiplication" title="Permalink to this headline">¶</a></h2> |
@@ -411,9 +412,11 @@ <h2><span class="section-number">1.3. </span>Invertibility and inverses<a class= |
411 | 412 | e_1 & e_2 & \ldots & e_m |
412 | 413 | \end{pmatrix}\\= ZA.\end{aligned}\end{align} \]</div> |
413 | 414 | </div></blockquote> |
414 | | -<p>We call <span class="math notranslate nohighlight">\(Z\)</span> a (left) inverse of <span class="math notranslate nohighlight">\(A\)</span>. (Exercises: show that <span class="math notranslate nohighlight">\(Z\)</span> is |
415 | | -the unique left inverse of <span class="math notranslate nohighlight">\(A\)</span>, and show that <span class="math notranslate nohighlight">\(Z\)</span> is also the unique |
416 | | -right inverse of <span class="math notranslate nohighlight">\(A\)</span>, satisfying <span class="math notranslate nohighlight">\(I = AZ\)</span>.) We write <span class="math notranslate nohighlight">\(Z=A^{-1}\)</span>.</p> |
| 415 | +<dl class="simple"> |
| 416 | +<dt>We call <span class="math notranslate nohighlight">\(Z\)</span> a (left) inverse of <span class="math notranslate nohighlight">\(A\)</span>. It can be shown that <span class="math notranslate nohighlight">\(Z\)</span> is the</dt><dd><p>unique left inverse of <span class="math notranslate nohighlight">\(A\)</span>, and that <span class="math notranslate nohighlight">\(Z\)</span> is also the unique right |
| 417 | +inverse of <span class="math notranslate nohighlight">\(A\)</span>, satisfying <span class="math notranslate nohighlight">\(I = AZ\)</span>. We write <span class="math notranslate nohighlight">\(Z=A^{-1}\)</span>.</p> |
| 418 | +</dd> |
| 419 | +</dl> |
417 | 420 | <p>The first four parts of the next theorem are a consequence of what |
418 | 421 | we have so far, and we shall quote the fifth and sixth (see a linear algebra |
419 | 422 | course).</p> |
@@ -513,6 +516,8 @@ <h2><span class="section-number">1.4. </span>Adjoints and Hermitian matrices<a c |
513 | 516 | <span class="proof-type">Exercise 1.16</span> |
514 | 517 |
|
515 | 518 | </div><div class="proof-content"> |
| 519 | +<p>(This is an advanced exercise if the other exercises are complete. |
| 520 | +If you are behind on the exercises please skip this one.)</p> |
516 | 521 | <p>Consider a matrix <span class="math notranslate nohighlight">\(A=B + iC\)</span> where <span class="math notranslate nohighlight">\(B,C\in\mathbb{R}^{m\times m}\)</span> |
517 | 522 | and <span class="math notranslate nohighlight">\(A\)</span> is Hermitian. Show that <span class="math notranslate nohighlight">\(B=B^T\)</span> and <span class="math notranslate nohighlight">\(C=-C^T\)</span>. To save |
518 | 523 | memory, instead of storing values of <span class="math notranslate nohighlight">\(A\)</span> (<span class="math notranslate nohighlight">\(m\times m\)</span> complex |
@@ -915,7 +920,7 @@ <h2><span class="section-number">1.10. </span>Constructing orthogonal projectors |
915 | 920 | <div class="clearer"></div> |
916 | 921 | </div> |
917 | 922 | <div class="footer" role="contentinfo"> |
918 | | - © Copyright 2020, Colin J. Cotter. |
| 923 | + © Copyright 2020-2022, Colin J. Cotter. |
919 | 924 | Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 4.2.0. |
920 | 925 | </div> |
921 | 926 | </body> |
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