ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sun, 21 Jul 2024 09:25:26 +0200Is there a "compound matrix" method for matrices?https://ask.sagemath.org/question/78333/is-there-a-compound-matrix-method-for-matrices/I'm surprised that if `A` is a matrix that there isn't a `A.compound_matrix(r)` method.
The `r`th compound matrix can be constructed as
Cr = matrix(A.base_ring(), binomial(A.nrows(), r), binomial(A.ncols(), r), A.minors(r))
Writing a function to do this is trivial. However, it's such an important construction that I'm surprised it's not built-in.
Is it possible that I'm overlooking another method that builds the `r`th compound matrix?Fri, 19 Jul 2024 18:19:10 +0200https://ask.sagemath.org/question/78333/is-there-a-compound-matrix-method-for-matrices/Comment by FrédéricC for <p>I'm surprised that if <code>A</code> is a matrix that there isn't a <code>A.compound_matrix(r)</code> method.</p>
<p>The <code>r</code>th compound matrix can be constructed as </p>
<pre><code>Cr = matrix(A.base_ring(), binomial(A.nrows(), r), binomial(A.ncols(), r), A.minors(r))
</code></pre>
<p>Writing a function to do this is trivial. However, it's such an important construction that I'm surprised it's not built-in.</p>
<p>Is it possible that I'm overlooking another method that builds the <code>r</code>th compound matrix?</p>
https://ask.sagemath.org/question/78333/is-there-a-compound-matrix-method-for-matrices/?comment=78349#post-id-78349The usual name is "exterior power". It seems this is not yet implement on morphisms. Using "git grep" on the code base finds these words about various kinds of modules.Sun, 21 Jul 2024 09:25:26 +0200https://ask.sagemath.org/question/78333/is-there-a-compound-matrix-method-for-matrices/?comment=78349#post-id-78349