[LON-CAPA-users] coding a customresponse problem using &cas()

[Justin Gray]

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 <kortemey at msu.edu> wrote:

> Hi Again,
>
> > On May 25, 2015, at 9:49 PM, Justin Gray <jgray at 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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