This is the new home for the CAS I have been making. It is now in the 'Your Projects' thread because I have actually started to code the CAS and also because I think more people will actually go here instead of 'Suggestions'. Anyway, here is the opening post:

In a few weeks, I will be going to Puerto Rico to visit family. That would be all fun if it wasn't for one thing: The Long Plane Ride! While brain-storming ideas about what to do with my year-old TI-84+ SE, I thought of an idea: a CAS. A CAS has long been on top of my list of what I would like in the TI 83+/84+ and I have decided that since no one has made a good one yet (Symbolic won't do CAS automatically) I am going to take matters into my own hands. In return for me coming up with the pseudocode and some very basic code by the time I get back, I would at least like a veribality test on how this program would work and/or be need to be coded. My best programming abilities are with TI-Basic and Axe. So, unless anyone has a better idea, it would be programmed in Axe. I know people might say, "This is a very ambitious project." I provide a solution: open-source. Whenever I, or someone else, makes an improvement to the code, that improvement would be posted here in this thread. I would very much like comments about the CAS.
Important stuff fom the old topic here:

FOIL of the form (ax+b)(cx+d)

KermMartian wrote:
Well, generally a CAS is a lot more general. It first takes an equation in symbolic string form (like ax+b(c+dx)), performs operations called lexing and parsing to reduce the input to some kind of tree (here, first add c and d times x, then multiply the result by b, then add that result to a times x). Then, it can use a set of rules to simplify. For example, using constant multiplication rules, it can simplify to ax+bc+bdx (in its tree form, not in string form). Next, it can combine coefficients to get (a+bd)x+bc. Finally, it can see there are no more simplifications to apply, convert its tree (or AST) back to a string, and show that to the user.

AHelper wrote:
You could always look into the gCAS/gCAS2/Graph3DP threads.

For how trees can be used for math, look at a gif generated by gCAS2 doing evaluation:

Something new I just found here:

(a + b)2 = a2 + 2ab + b2
(a + b)3 = a3 + 3a2b + 3ab2 + b3
(a + b)4 = a4 + 4a3b + 6a2b2 + 4ab3 + b4
EDIT: with contest #10 going on, getting ready for a week away from home, and the Puerto Rico trip, CAS8x will temporarily be put on hold.
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