## 291 Reputation

18 years, 66 days

## I could not disgree more....

I am a Maple ambassasor and I encourage students to use Maple routinely as an aide in learning and doing math and I designed and implemented a course in using Maple to do just that. I also use Maple frequently in my research. Frankly, I don't give a hoot what is under the hood and I don't care how Maple works. I only care that it works. Mutable and immutable are totally unimportant until you get to large arrays; memory locations are Maple's concern, not mine. If V is an eigenvector of the matrix M with eigenvalue 7 I want the answer to the question is ( MV = 7V)  to be yes. That is what Mathematica answers, that is what every mathematician and physicist woud answer, that is the answer that would not confuse a student. I surely do not want to read help pages. I have always told my students to ignore everything on the help pages (at first go) and head for the examples at the end. A couple of those will get you on your way.

Times have changed. NO ONE reads instructions, every device comes with a quick start booklet. We do NOT teach our students hexidecimal notation so they can communicate with computers; we teach computers to deal with decimal notation. (My kids WERE taught hexidecimal.)

The issue is NOT mor subtle; the implementation is just not wise or practical.

## you are too generous...

@ I agree that Maple is an older CAS but I think it has real strengths compared to newer languages. The problem I raised involves priorities-does a definition conform to standard mathematical usage or should some pretyy obscuure programming concern take precidence. Just as basic commands like plot can be modified to use fancy fonts for labels or to add titles by those to care to read the fine print one should get a true as an answer to the question is (Sv=Tv) in my example and a false to an inquiry of the form is(location Sv=location Tv).

## mystery solved...

@ Thank you for clarifying. I do not think Maple would be usable without the helpful responses on Maple Prime.

However, from a marketing point of view Maple has always excelled at simplicity of use, e;g;, plot or solve or fsolve are all easy to use out of the box with pretty obvious meaning and syntax. When the question of equality of two vectors refers to their storage locations rather than to their values that is VERY far from the obvious mathematical meaning. I would call it extremly eccentric with the potential to truly confuse students. I can certainly understand that the locations etc. might be of importance in certain situations I think making it the default is a bad design decsion.

## Thank you for clarifying that....

@acer Thank you for clarifying that for me.

## I missed that....

@ecterrab Thanks for repeating; I missed that. Muito obrigado!

## very nice but.....

@ecterrab How do I set one of the constants = 7 for example?

I tried c[1]:=7 but that does not work.

## It is mysterious but that is okay....

I corresponded with tech support about the 4/6 post about the length command and they clarified it for me.

"Maple development team say that the "formula" used for length was not designed to be clear to users, but instead, to be as fast as possible to compute given the internal representation. It is used a lot for intermediate steps in internal computations."

In other words, it is mysterious-not meant for casual users.

## length?????...

I do not understand the example:

length (x+2y) = 9

but I note that
length(x+1) = 9 also.

(Maple 2022)

In fact, it seems very mysterious.

## ah ha!...

@Joe Riel Thank you for explainng that.

## good catch but...

@mmcdara

In fact I would be happy with [123,0,321]; they are data points in range 0 to 1000.

## Very good but mmcdara 3548's caught a p...

I am still curious why convert("531",integer) gives that error message.

Origin of problem: I generated a long list of 3 digit numbers that I wanted to plot. However, I did not notice that there were no spaces or commas betwen the entires. I was trying to salvage all that typing.

I tried these simple procedures that fail and I was curious about Maple's pattern matching capabilities. (I think this would be very simple in Mathematica.)

f:=proc (x) if x= "y" then y end if end proc;
or

f:=proc (x:: "y")  y  end proc;

## thank you for the suggestion...

Since h(0,x) =diff(f(u,x),x) at  u = 0 and f(0,x) = g then h(0,x) must be diff(g,x) to be consistent. I should have mentioned that I tried that for another dead end. Here is the message:

Error, (in pdsolve/numeric/match_PDEs_BCs) cannot handle systems with multiple PDE describing the time dependence of the same dependent variable, or having no time dependence

## Thx...

I checked kernelopts(floatPi); in both Maple 2019 and 2020 and got true in both cases.

However, I realized from your answer that I got the wrong answer when Digits was set to 10 but if I put Digits:=15 all was well. I guess I was seeing round off error.

## good to know...

@Carl Love  That is quite subtle. Good to know. Thank you. I guess the longer displayprecision

is the command I will have to use.

## my evalf error...

Thank you for explaining my error. As Tom Leslie also pointed out using evalf( ....,5) was my problem.

From the syntax-it sure looks like a composition- I assumed that since  f(g(x)) is computed by first computing g(x) then applying f to that result evalf( eval([W,Wp],nans(1.5)),5) would be computed by first evaluating eval([W,Wp],nans(1.5)), then applying evalf..., 5) to that answer.

In my work I was using dsolve with Digits:=35 and error tolerances of 10 ^(-14). I guess evalf overrides those instructions somehow. So be it.

The interface setting does resolve my issue.

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