[TI-M] Can TI-89 do this math?
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[TI-M] Can TI-89 do this math?
Hi:
I'm considering buying a TI-89 to have a calculator that can better
assist me at times when I can't remember some things like trig
identities and basic integral tables. I have TI-83, but that is a lot
of trouble to use to verify identities, and I have to be pretty sure of
then to start with.
But I am doubtful about the TI-89's symbolic math abilities. I went to
a store and tried to do a one-sided Laplace transform of some simple
functions, which it failed to evaluate. Then it occurred to me after I
left that maybe it could have done it in two parts.
I tried:
integrate( e^(s*t)*t,t,0,infinity )
which returned "undef" or maybe infinity, I forget. And I tried:
integrate( e^(s*t)*sin(t),t,0,infinity )
An astute reader will recognize that I made an error in that the Laplace
transform should have a minus sign in the exponent of e. However, this
has little effect on the outcome, as the result returned from the first
integral should look something like:
1/s^2 if Re(s)>0, else undef
and so the case of a positive exponent would simply cause the condition
to be if Re(s)<0.
Can the TI-89 accept assumptions that would make it return a result in
this case?
Another approach would be to evaluate the definite integral such as
integrate( e^(s*t)*sin(t),t,0,x )
then take the limit as x->infinity. But this still needs the assumption
that Re[s]>0.
Can TI-89 take assumptions in either the integral or limit operations?
Any other methods to evaluate this integral or ones like it?
--
_____________________
Christopher R. Carlen
crobc@earthlink.net
Suse 7.3 Linux 2.4.10