works OK for me in Maple 2024.1

Download works_for_me.mw

@C_R 

Both solutions are correct, but the separable one requires assumptions to obtain zero result from odetest while the dAlembert one does not. In this sense, the dAlembert solution is preferable.

Download difference_in_separable_and_dalembert.mw

I guess the rule of thumb here is this:

If we can find a method to solve non-linear ode in y', as in this example,  without first having to solve for y' , then use that method.

The dAlembert method does that, it does no require isolating y' first.

While in the case of solving as separable, we have to first solve for y' to isolate it, and then solve the resulting ode as seprable. This is the main difference I see.

I solved this ode by hand using both separable and dAlembert methods. I see nothing wrong with the separable approach, this is how we solve this at school. The only difference as I said, is we have to isolate y' first. And this seems to be the cause of the trouble even though I can't still see why and what is wrong with doing that. May be someone can see the subtle mistake if any in the separable solution method.

@Kitonum 

Thanks, I think the Maple 2024.1 gives the correct solution, not Maple 2018, because this Clairaut  ode can only have one general solution and possibly a number of singular solutions (if they are valid ofcourse).

In the above result from Maple 2018 you show, only the first general solution must be the correct one and all the others are not. 

Singular solutions do not have a constant of integration in them. So this looks like something that was fixed in later version of Maple after 2018 or in Maple 2024.

But the strange thing I was asking about are those warning messages.

I do not yet know what causes them and why they go away when trying the command one more time and do not think I saw them before from calling dsolve. They seem to be new.  I do not have Maple 2024.0 to check.

@dharr 

Oh, yes ofcourse. Phase plot does not work for non-autonomous system of odes. I completely forgot that when I was looking at this. It will be nice if Maple issues a WARNING message to alert the user so they know :)

it looks like Maple does not have the cos(2*x) trig relations (double angle trig) in its lookup tables.You could help it by using simplify with side-relation

e:=1/2 + cos(2*x)/2;
simplify(e,{cos(2*x)=1-2*sin(x)^2}):
simplify(%);

btw, the intutive thing for the user is just to do simplify() and nothing else. This is what another software does

In Maple one has to try 10 different things to get the answer. Nothing new here. See my recent question on Limit where the same thing there. One has to try different things to find which one works.

@ecterrab 

good news. After rebooting my windows 10 PC, now the error installing V 1780 is gone! And now dsolve works

No error like before. I have no idea why restarting the PC was needed. There is no protection issues on the folder that Physics uses to install to. Never touched that. There was something causing the update to fail and rebooting fixed it. 

Download divide_by_zero_maple_FIXED_2024_1_august_6_2024.mw

Next time I get this error updating Physics, I will reboot the PC and try again.  

Thanks for the help.

@C_R 

How did you manage to show the JDK version column there in task manager? I can't see how to show this on my task manager;

I do not think I have any other windows application that uses JDK, at least for GUI that I know above. Matlab does not, Mathematica does not. Scientific work place does not. notepad++ that I use does not. Word does not.

It is only Maple that I know uses Java for GUI. 

This is a brand new windows 10 installation, so I think everything is up-to-date. I took the PC to best buy and they installed windows 10 fresh since my C drive died and everything is new. But I will double check again that graphics drivers are update to date or not.

@Ronan 

Displays show the right monitor as primary (the one I get shaking on) because it says "1" on it. the  left monitor says "2". Is this right? This makes the right one the primary? And when I scroll down it has the checkmark set on it. So the right monitor is the primary. I also checked by clicking "DETECT" and it is correct.  

I will try swapping them by making the left monitor primary instead as you suggested and reboot windows and see if this fixes it.  

if you google using this search 

                              "maple" "book" "dynamics systems"

gives number of links to books on dynamics systems with Maple code.

A free version of the book Dynamical Systems with Applications using Maple is here

@ecterrab 

Thanks for looking  into this. This is brand new windows 10 installation and have nothing at all in my Maple ini files. I have not touched or changed anything related to Maple .ini files.

I just tried command line, and it gives same exact error:

Now I run it (right click on image and say open in new TAB to see it magnified)

I think the Physics update I made did not go through. But I actually did another Physics:-Version(latest) after that just in case, and it told me I have latest physics.

My guess now is that it only updated the Physics version number, but the bits themselves with your fix were not installed physically on my PC.

This explains why version number is up-to-date but date is still old and the bug is still there.

I will try to check where Physics updates go to on disk and see if I can spot something. 

Btw, is there an option to force Physis to update even though it says I am using latest version? something like

           Physics:-Version(latest,force_update)

Or a way to safely remove  latest version of Physics so I can try to install it again? If it was problem with update this should fix it hopefully.

Update

I think I found the problem. As I suspected, Maple only updated the version number but not the actual Physics update !

Here is screen shot. Notice the date on the files

So I think it was just installation problem. I just need now to find how to tell Maple to reinstall again latest Physics version. When I open the file version.txt is says

package-title: Physics Updates
cloud-id: 5137472255164416
cloud-version: 1780
cloud-link: https://maple.cloud
install-date: 2024-08-06 20:17

But Physics update.mapl is still the July 25 version !

It seem Physics updates the version number first, then next it downloads the actuall updates.

If this fails for some reason we end up with an inconsistent state where version number is updated but the bits on disk are not.

These two steps (updating the version number file and updating the actualy library) should be done as one single transaction. So if one fails, then both are not updated.  

Update 2

I found why. I just did Physics:-Version(1779);  then close all Maple. Started it again. Then did Physics:-Version(latest); and got same message as before. Sorry I forgot to mention it

Now close all of Maple. Start again

You see? It says it is using V 1780. But actually it never updated it due to the above error. On disk I just looked at , it is stll showing the Maple Physics dated July 25 version. 

It did however update the version.txt file.

So the problem is because Maple Physics did not update due to the above error. 

I will try rebooting the PC and try again and see if this fixes whatever the problem is with Physics update.

I am not using firewall or anything. Normal Windows 10 installation. direct connection to internet with cable modem.

I think the Physics update should not update the version.txt file before it updates the Physics library. It should do it after that and only if updating Physics library was successful.

@Thomas Richard 

I forgot to also mention that when this happens, i.e. shufflings starts, which I noticed happens only on my right monitor, then if I move the Maple window to the left monitor, the shuffling stops and Maple go back to normal.

When I move the window back to the right monitor, the shuffling starts again !

I had these two monitors for years and Maple always worked OK on them. This only happens on Maple 2024.1.

I just checked, they both have same resolution and same refresh rate. I have not touched or changed anything of this. They both 36 in wide monitors. 

If the problem with the graphics adaptor, then I would see this in other applications, right? But it is only Maple which does this. But restarting Maple fixes it for few hrs until it happens again.

@vv 

I also did not know about these two examples you show. But they fall into the same question I have here.  Which is:

Why limit says there is no limit on its own and needs additional post-processing to make limit work, and how is a user supposed to know this.

I have always thought that if limit returned unevaluated then limit do not exist.   Now I find the limit can exist but one needs to do additional calls to find out.

I always thought that if Limit fails, then limit do not exist. Period. Now I find limit can exist but need to simplify or some conversion and so on. 

So my question here is asking, why limit on its own does not find the limit if it exists by trying different approaches itself?

Note that I am NOT adding assumptions in the post-processing call, which can provide more information to limit to make it give different result.

I am simply calling simplify on the result. This made limit evaluate. Simplify provides no more information to limit than it had.

So now I have to call simplify or expand or convert and may be 10 other post-processing calls each time after calling limit just to see if limit actually exist or not.

This for me is wrong design of limit. 

@vv 

Because this is separate and different question.  

This is asking why one needs to use simplify to make limit work and evaluate.

The other question asked why Limit did not work.

I find it hard to see how you think these are the same question. Just because the question is using same example, does not mean they are asking same thing.

At stackexchange this how things works. When one has a follow up and new question on a subject they asked (limit in this case), they are asked to open new question. No one there likes one to update their question and ask something more once the question is asked.

@ecterrab 

Thanks. But for some reason, I still get division by zero on my end. 

Download divide_by_zero_maple_V2_2024_1_august_6_2024.mw

I am on windows 10. I think you mentioned once that you use Mac, right? Could this make a difference? 

I closed Maple and opened twice, same result.  btw, I do not know why Physics:-Version() says that it was created on July 25,2024. Should not the date of V1780 be today August 6,2024? May be the update did not actually go through but only the version changed? I do not know.

I updated using the same way I always do, Physics:-Version(latest);  then closed all of Maple.

@Mariusz Iwaniuk 

Thanks., Easier workaround I found is to just call simplify on the original result which still had limit stuck in it. This causes limit to now evaluate. Strange behavior. Asked separate question on this.