Re[2]: [MATHEDCC] Algorithms used in TI-92

yoshiwbw@SMTPLINK.LACCD.EDU
Tue, 11 Mar 97 19:39:31 pdt

There is something called a Risch algorithm (I'm only
guessing at the spelling) that Mathematica and Maple both
use for finding antiderivatives. Obviously I don't know
much about it, but I believe it's supposed to be well known.
Derive and the TI-92 evidently use a different algorithm
since they give different anti-derivatives than Mathematica
and Maple. My favorite example is to find the indefinite
integral of 1 / (2 + cos x) . Derive and the TI-92 both
give correct answers, Maple and Mathematica are clearly
wrong--their antiderivative of our positive (continuous)
function is periodic and discontinuous. (Yeah, yeah, it
works on one inteval of length pi.)
Bruce Yoshiwara

-----------------------------------------------------------------
>Date: Tue, 11 Mar 1997 18:56:34
>To: liano greg <gliano@monet.csc.vill.edu>
>From: Brian Smith <smithb@management.mcgill.ca>
>Subject: Re: [MATHEDCC] Algorithms used in TI-92
>
>At 02:08 PM 3/11/97 -0500, you wrote:
>>March 11, 1997
>>
>> Does anyone know what type of programming algorithms are used on
>>the TI-92 (I know it uses Derive) to find antiderivatives. Does it
>>parse the entries to find certain forms and then perform, for instance,
>>a trig substitution? Or does it solve every problem with some general
>>approach. In other words, does the TI-92 find antiderivatives the same
>>way as we might teach by hand?
>>
>>Greg Liano
>>gliano@monet.vill.edu
>>
>Greg:
>
>You ask an interesting question! It seems to me that it must somehow
identify the type of integral and use the appropriate "method of
integration" - if there is a general approach I would sure like to know what
it is. With your permission I will post the question to the GRAPH-TI list.
>
>Brian
>

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