Alfonsa Garcia*, Francisco Garcia, Felix Alonso, Agustin de la Villa,
Sara Hoya, Gerardo Rodriguez (Spain), garcial@eui.upm.es,
avilla@dmc.icai.upco.es, gerardo@gugu.usal.es

Some Unexpected Results Using Computer Algebra Systems

Sometimes, when you are using a computer algebra system (CAS), you introduce
the input and the computer does not react as you expect.  Usually it's very
difficult to know the reasons of such answer and what to do for solving the
problem.  In this paper we see how the teacher can often profit these
unexpected outputs to reinforce concepts and mainly to show the students they
have ever to control the computer and they have ever to control the computer
and they must always check its results.  We present different examples where a
CAS like DERIVE, MAPLE or MATHEMATICA does not work as it is should and we
propose how use them as a pedagogical tool.  We like to show different
unexpected situations that you can find in a very wide context like bugs,
limitations, good but surprising answers, etc.