## Diophantine equation...

As a newbie in Maple2024, my next step is to try to solve a Diophantine equation. Attempts with isolve failed. It is the famous task B3 from the IMO of 1988:

If for integers x and y the fraction (x^2+y^2)/(1+x*y) is a positive integer, then it is actually a square number.

The solution is well known. But I would like to learn how to use Maple using this example and would like some advice.

Best regards, Alfred_F

## undefined in DataFrame, how to ignore?...

Dear Power Users, Dataframes are a powerful tool within Maple. However, when I have 'undefined' in cells "Aggregate" or "DataSummary" does not provide answers. However, when I use "Statistics:-Mean" with the additional option "ignore=true" I can get an answer for one column (see attached worksheet). Adding "ignore" to aggregate apparently does not work. What is the method for ignoring the undefined data? In Excel when a cell is blank it will be ignored. Thank you for any help given.MP_Aggregate.mw

## why Maple help pages is such a mess? How to make i...

Maple help pages keep getting worst with each release.

I want all input to be displayed using Maple 1D notation, so I can copy the example to my worksheet since I only use worksheet and not document (2D) mode.

So even though the first thing I do when I open help it to turn off the

view->Display examples with 2D

So it is no longer checked, I still see many pages using 2D math for input.

Here is one example ?D  page

If I copy one such input to my worksheet now it looks like this

eveything in 2D becomes ?? when I copy it.

So one can only look but not copy?

Is there any other option to make sure, really make sure, all examples have 1D as input?

The problem is that it is all not consistent. Some examples have a mix of 2D and 1D as the above page. Some are in 2D and some are in 1D.

And this is all on the same help page!

Does no one inside Maplesoft even look at their own help pages?

## Error, (in evala) reducible RootOf detected. and s...

Maple solves this first order ode correctly and solution verifies OK. The solution is explicit and has RootOf. I asked it to solve it using dAlembert method to compare with my own solution using dAlembert.

Next I called dsolve on same ode and IC but asked for implicit solution now instead, then called solve on the implicit solution to see if it will give same solution y(x) as before (with RootOf). But instead solve gives this internal error

Error, (in evala) reducible RootOf detected.

Next called PDEtools:-Solve to see if it will give same error. It did not give error. But it also could not solve for y(x) either.

Any one has any idea why this error is generated by solve? Is this expected or not?

I was expecting same result as first call to dsolve which returned explicit solution. And why is PDEtools:-Solve do not generate same error? It must have run through different code path.

May be some one have some insight on this.

 > interface(version);

 > Physics:-Version();

 > libname;

 > ode:=(2*x+y(x))+(4*x-2*y(x)+1)*diff(y(x),x)=0; IC:=y(1/2)=0;

 > maple_sol:=dsolve([ode,IC],[dAlembert]);

 > odetest(maple_sol,[ode,IC])

 > maple_sol:=dsolve([ode,IC],[dAlembert],implicit);

 > #solve gives error sol:=solve(maple_sol,y(x));

Error, (in evala) reducible RootOf detected.  Substitutions are {RootOf(6*RootOf(_Z^2-41,index = 1)*_Z+41*_Z^2+5,label = exptmp) = -5/41*RootOf(_Z^2-41,index = 1), RootOf(6*RootOf(_Z^2-41,index = 1)*_Z+41*_Z^2+5,label = exptmp) = -1/41*RootOf(_Z^2-41,index = 1)}

 > #PDEtools:-Solve  gives no error but does not solve it sol:=PDEtools:-Solve(maple_sol,y(x));

 >

## Empty context panel: when does this happen ...

I am trying to understand under which conditions submenus disappear.

Now I have seen that the context panel is empty when submenues disappear.

Has anybody noticed the same and are there other instances when the context panel is emtpy?

Both effects could have the same rootcause.

Here is an example: