Hi Gerd, To test this in MAXIMA, one could add two additional conditions: 1. is(determinant(A)=0); (all idempotent matrices except for the identity matrix are necessarily singular) 2. is(not(rank(A)=0)); (the zero matrix is the only matrix with rank 0)
Thanks, Justin P.S. To avoid confusion, I think the variable $determinant should be renamed as $idempotent Justin Gray | Senior Lecturer Department of Mathematics | Simon Fraser University 8888 University Drive, Burnaby | V5A 1S6 | Canada Tel: +1 778.782.4237 On Tue, May 26, 2015 at 4:36 AM, Gerd Kortemeyer <korte...@msu.edu> wrote: > Hi Again, > > > On May 25, 2015, at 9:49 PM, Justin Gray <jg...@math.sfu.ca> wrote: > > > > P.S. Ideally, I would like to stipulate that students provide a > nontrivial example (excluding the zero matrix and the identity matrix) but > that is the topic of another discussion. > > I don’t know enough MAXIMA. How would you test for this in MAXIMA? > > is(A=(0)) > is(A=([1,0],[0,1])) > > Would that catch it? > > And if they enter that, should they be charged a try? > > - Gerd.
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