FlowCE: Calculus on your TI-84 Plus CE | Hacker News Reader

FlowCE: Calculus on your TI-84 Plus CE

tommyb3ll.github.io

51 pointsjgx025 comments

I wonder who would install this onto their calculator in earnest. Like, who’s the segment of folks with the savvy to learn about this and install this on their TI calculator, but who aren’t savvy enough to just learn to do the computations in curricular calculus class?

I used to use a TI-89 in high school, which had a calculus-enabled CAS built-in. It was really handy for checking my work and for working on components of problems. And if you're in a class where the work is more applied math, like physics, it's really helpful so that you can think of the overall problem without getting bogged down in the computation.

I definitely would’ve installed it as a kid. It’s not about the computations it’s about doing it with style.

There is absolutely an overlap in those two circles. The venn diagram is almost exclusively people who are heavily motivated by novelty and hate the drudgery of actual work. I have been a pathological member of that particular venn diagram overlap for my whole life. It's exactly as maladaptive as you might imagine.

What's really novel and innovative about this is that you just plug the calculator into your computer and press install.

I 'cheated' in my Astronomy 1001 class by reverse engineering some sort of moon phase calculation I was supposed to do every day, by hand, for a month.

I didn't want to check the location of the moon at the same time every day so I just worked out the math instead, and then fudged the numbers on the worksheet so they wouldn't look too perfect.

I did this back in...1999 or 2000, I think? Apparently kids are still doing the same silly assignment a quarter century later: https://www.reddit.com/r/uofmn/comments/1km6zzv/comment/mseh...

I feel like this would describe me to a T.

Highschool nerds, that is why there are plenty of CASIO graphical calculators with this stuff built-in.

Which are quite common outside US, where the TI monopoly with the education system doesn't exist.

Cool! Is it based on KhiCAS for the CG50 (the one with the extremely confusing documentation)?

Also doesn't this pose a risk of being used in math exams? I remember hearing a kid in my high school trying to cheat through the aforementioned.

It cites sources including KhiCAS at the end of the page.

In college they have a docking station for calculators that used the two metal tabs on any “permitted for use on tests” model that locks them into secure testing mode for the duration, which would inhibit access to the program menu. Unsure if lower ed schools have these but TI’s been in the monopoly long enough to have propagated them, and this exact thing is 100% of why they’re so hostile about patching the OS to disallow usermods and machine code: their monopoly’s benefit to customers is that they fight modders. I suspect those school docks also force a firmware update, but haven’t verified as it’s quite expensive an object to brick and risky to my education to find out.

Snap judgment, but it appears to be a vibe coded interface added to an existing CAS for a TI-84 Plus CE calculator.

I can run Maxima on my phone. Heaven!

It's most likely based on the Poor Man's Integrator (amongst other tricks)

https://mathoverflow.net/questions/67727/the-easiest-symboli...

Treasure trove for people into this sort of thing https://www.researchgate.net/profile/Robert-Dr-Kragler

is this just a total guess? the repository says it's forked from KhiCAS, which is a ti84 port of Giac/Xcas, which can do full Risch integration if necessary

https://github.com/KhiCAS/ti-ce-giac/blob/main/kintg.cc#L288...

Flow CE is unlikely to have the full risch.. one could compromise with, "pmint with risch characteristics"

i don't see any changes in the fork of KhiCAS's giac that would suggest something like that.

https://github.com/tommyb3ll/ti-ce-giac https://github.com/tommyb3ll/ti-ce-giac/blob/main/kintg.cc#L...

why do you think it's unlikely? if KhiCAS does it, why wouldn't this fork?

Alright. I jumped to conclusions skimming that kintg.cc (before a risch call would even be considered)

Parts of it looked very much like pmint's core tactic of matching coefficients (given a form)

Can a Ti-85 do this?

The page says:

> FlowCE fills most of the calculator's memory (2.8 MB)

The ti-85 only had 28kB ram according to wikipedia.

So yeah, won't fit.

Ti-85 seems to do some calculus out of the box

https://en.wikipedia.org/wiki/TI-85

TI85 can do very basic calculus-like things, such as estimating numeric slope at a point on a graph, and numerical area under a curve. Those correspond to derivative and integral.

Appears to have an equation solver built in.

Numeric only. It's a zero finder.

Thanks!

It's certainly a valuable tool when doing calculus. I used one while taking calculus and other undergrad math.

However, it does not include a computer algebra system and does not help with symbolic evaluation of integrals or derivates, which I believe is what this FlowCE thing is supposed to do.

The ti-92 and ti-89 have some of this built in, but they have a much larger ROM and use a 32-bit processor instead of an 8-bit processor.

The ti-84 plus ce that this runs on is much newer, has a significant amount of user accessible flash and while the processor is still 8-bit, it runs much faster; computer algebra needs a pretty good amount of code, and the earlier ti calculators, like the ti-85 just don't have enough storage for that, and probably not enough computation to make it reasonable to use if it had enough storage.

Appreciate this insightful post.

Symbolic evaluation is definitely a different level.

The ti 85 is definitely old, it used to still be more capable than the ti84 but the difference between the ti84 of the past and today is clearer.

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