Re: 49G+ CAS oddities, help!

In article <pan.2006.02.17.08.03.48.186462@xxxxxxxxxxxxxxxxxxxxxxx>,
smthmlk <sorry@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

I've been using the 49g+ for three weeks, several times per day, everyday
(taking calc & physics classes at the moment). I've been enjoying learning
the features of this calculator, however the CAS throws me for a loop with
some of its output. An example I came across tonight:

differentiating y=(tanx - 1)/secx

I'm inputting: dervx((tanx-1)/(1/cosx)) or: dervx(cosx(tanx - 1))

From my work on paper, I get y'=cosx+sinx. The TI89 (original) gives me
y'=cosx+sinx. However, the hp 49g+ spits out some unruly answer that,
while correct, really isn't useful to me, and is more complicated than
what you get from the quotient rule's immediate output (with no
simplification). I've run the output from dervx through SIMPLIFY() only to
receive another crazy answer that isn't closer to the fully simplified y'.

I'm not sure if I have some flags set incorrectly, or if I'm just retarded
and can't comprehend the importance of outputting y' this way. I'm using
rom 88 from hpcalc.org

Am I doing something wrong? Is this a problem with the 49G+'s CAS? Am I
just retarded? Thanks so much for any tips to help me understand the
CAS on this beast :)

-Trevor

The HP49+ is a bit weird on simplifying trig expressions, particularly
ones with TAN functions mixed in with either SIN or COS.

Something like TAN2SIN followed by EVAL works on many of them, including
yours.
.

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