## 19 Badges

12 years, 54 days

## why dsolve gives division by zero on thi...

Maple 2024

I do not have earlier Maple version to check now. But Maple 2024.1 gives division by zero on this second order ode with missing x. This looks like new problem in Maple. Would someone who have access to earlier version of Maple be able to check if this problem shows there also? I solved this and get y=x+3 as solution which Maple verifies.

 > interface(version);

 > restart;
 > ode:=diff(y(x),x\$2)=(diff(y(x),x))^3-(diff(y(x),x))^2; IC:=y(0)=3,D(y)(0)=1;

 > dsolve([ode,IC])

Error, (in dsolve) numeric exception: division by zero

 > sol:=y(x)=3+x; odetest(sol,[ode,IC])

 > DEtools:-odeadvisor(ode);

 > infolevel[dsolve]:=5;

 > dsolve([ode,IC])

Methods for second order ODEs:

--- Trying classification methods ---

trying 2nd order Liouville

trying 2nd order WeierstrassP

trying 2nd order JacobiSN

differential order: 2; trying a linearization to 3rd order

--- trying a change of variables {x -> y(x), y(x) -> x}

differential order: 2; trying a linearization to 3rd order

trying 2nd order ODE linearizable_by_differentiation

trying 2nd order, 2 integrating factors of the form mu(x,y)

trying differential order: 2; missing variables

-> Computing canonical coordinates for the symmetry [0, 1]

-> Rewriting ODE in canonical coordinates by means of differential invariants

Try computing 1 more symmetries for ODE written in canonical coordinates

-> Computing symmetries using: way = 3

Found another symmetry:

Found another symmetry:

Computing a convenient ordering to use the 3 symmetries available

<- differential order: 2; canonical coordinates successful

<- differential order 2; missing variables successful

Error, (in dsolve) numeric exception: division by zero

 > dsolve(ode)

Methods for second order ODEs:

--- Trying classification methods ---

trying 2nd order Liouville

trying 2nd order WeierstrassP

trying 2nd order JacobiSN

differential order: 2; trying a linearization to 3rd order

--- trying a change of variables {x -> y(x), y(x) -> x}

differential order: 2; trying a linearization to 3rd order

trying 2nd order ODE linearizable_by_differentiation

trying 2nd order, 2 integrating factors of the form mu(x,y)

trying differential order: 2; missing variables

-> Computing canonical coordinates for the symmetry [0, 1]

-> Rewriting ODE in canonical coordinates by means of differential invariants

Try computing 1 more symmetries for ODE written in canonical coordinates

-> Computing symmetries using: way = 3

Found another symmetry:

Found another symmetry:

Computing a convenient ordering to use the 3 symmetries available

-> Calling odsolve with the ODE diff(_b(_a) _a) = _b(_a)^3-_b(_a)^2 _b(_a) HINT = [[1 0] [-_a+y -_b*(_b-1)]]

*** Sublevel 2 ***

symmetry methods on request

1st order, trying reduction of order with given symmetries:

1st order, trying the canonical coordinates of the invariance group

<- 1st order, canonical coordinates successful

<- differential order: 2; canonical coordinates successful

<- differential order 2; missing variables successful

Download divide_by_zero_maple_2024_1_august_5_2024.mw

## Clearing all Typesetting effect...

Maple 2024

I set

```Typesetting:-Settings(prime=x,'typesetprime'=true); #this says to use y'(x) instead of dy/dx
Typesetting:-Suppress(y(x)); # this says to use y' and not y'(x)```

So that  y(x) and diff(y(x),x) display as   y and y'  and this works.

But I am not able to clear this effect without doing restart. If I do

`Typesetting:-Unsuppress('all'); #clear all`

It still display derivative as  y'(x)  instead of diff(y(x),x) as expected. So the Unsuppress('all') had only partial effect.

How to completely remove all typestting effects so that it returns to how it was and without doing restart?

Worksheet below. Looked at help page, but it is still not clear. All what help page says is to use Unsuppress(all) and that is what I did. I am using typesetting level extended if it makes any difference.

 > interface(version);

 > restart;
 > ode:=diff(y(x),x\$2)+diff(y(x),x)*y(x)+3*y(x)=sin(x);

 > Typesetting:-Settings(prime=x,'typesetprime'=true); #this says to use y'(x) instead of dy/dx     Typesetting:-Suppress(y(x)); # this says to use y' and not y'(x)

 > ode

 > Typesetting:-Unsuppress('all'); #clear all
 > ode

 > Typesetting:-Unsuppress(y(x));

Warning, no depencency for function y has been declared => ignored

 > ode

Download how_to_clear_all_typesetting.mw

## why 2024.1 now jumps to END of next exec...

Maple 2024

Something seems to have changed.  I do not now have Maple 2024.0 to check or earlier Maple's as I have to reinstall windows since my C:\ drive died.

I installed Maple 2024.1 new on windows 10 home edition.

I noticed now when evaluating the current cell, the cursor automatically jumps to next cell, which is what I want and how Maple always worked.

But now the cursor jumps to the end of the command in the next cell. Before, I could swear that not how it worked and it used to jump to the start of the next cell.

This makes it very confusing, as I keep looking for where the cursor is now.

Why was this changed in 2024.1? I looked at option and see nothing to change this.

Here is worksheet and small movie.

This is my display options

 > interface(version);

 > x:=1;

 > y:=3;

 > z:=4;

 > h:=4;

 >

Download cursor_jump_to_end_of_line.mw

Update

I tried to change the cursor size and thickness in windows 10 itself (using settings->Ease of access->Text cursor) and made it much bigger and restarted Maple but this had no effect. Cursor inside Maple remained the same.

I was hoping if there is a way to make the cursor bigger then this will make it easier to see where it jumped to when hitting enter.

It is bad, since the Maple cursor jumps to random places in the next cell. sometimes it jumps to the middle of the code in the next cell when there are more than one line there.

Here is a movie. Notice how it jumped to the start of the second line now in next cell in one case and not to the end of the code.

I can't believe no one at Maplesoft have noticed this and is able to fix it. This is ridiculous behavior. I spend few seconds each time I hit enter looking for where the cursor has landed as I keep looking at start of the next cell and it is not there. I could have 10-20 lines of code in one cell and have too look to find where the cursor is hidden in these 20 lines.

It natural for one to look for where the cursor is when woking and this makes it annoying. Hopefully someone can find a way to tell Maple to bring the old behaviour back where cursor jumps always to the start of the next cell.

## Problem using smart plot with multiple ...

Maple 2024

I switched to using smart plot in Maple since it makes it easier. Here is an example

```sol:=[-1/4*x^2, x];
plot(sol,legend=sol)
```

But sometimes it gives internal error, like in this example, because some of the list of solutions give complex over some x domain

```sol:=[-1/4*x^2, (-1/2-1/2*(-3)^(1/2))^2+(-1/2-1/2*(-3)^(1/2))*x, (-1/2+1/2*(-3)^(1/2))^2+(-1/2+1/2*(-3)^(1/2))*x];
plot(sol,legend=sol)
```

Luckily I can trap this error and workaround it.

The strange thing is that if I give it explicit x range, then it works. It now can remove the solutions which give complex values automatically

```p:=plot(sol,x=-4..4,legend=sol);
```

question is: Should not smart plot have done this automatically? That is why it is called smart plot.

i.e. remove those solutions that give complex values like the case the above?

Maple 2024.1 on windows 10

## why maple hangs on this plot command?...

Maple 2024

I am using the smart plot (i.e plot without giving the x=from..to) since I am generating these plots programmatically and better let Maple figure the best range to use.

But found Maple hangs on some solutions.

Here is an example

```restart;
sol:=1/2/cos(x)*(sin(x)^2+(sin(x)^4+36*cos(x))^(1/2));
plot(sol);
```

I waited for 30 minutes and nothing happened.

If I change the above command to

`plot(sol,x=-Pi..Pi);`

then it finishes instantly. It looks like Maple is stuck trying to find correct x and y ranges to use.

Is this known limitation  or smart plot or is this a bug?

Maple 2024.1 on windows 10.

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