## RedefineTensorComponent in Physics package...

The Library:-RedefineTensorComponent in the physics package has got some serious problems, I guess in the update. It is not assigning the components at the right location for a tensor of rank 4 and above. It is working for tensors of rank 1, 2 and 3. Can someone please look into the issue and help out?

I am attaching the code with an example to indiacate the problem. Redefine.mw

## Covariant derivative of a specific vector...

Hi there!

Sorry to ask, but I don't know how I can solve it in a smart way. I want to take the covariant derivative of a specific vector, whose components are specifically defined, which can be constant or some functions of the coordinates. But, as soon as I define that specific vector, the covariant derivative fails to compute, saying there are "too many levels of recursion". Let me show what I mean.

I have these two attempts to get this:

First attempt

 (1.1)

 (1.2)

 (1.3)

 (1.4)

 (1.5)

 (1.6)

 (1.7)

 (1.8)

 (1.9)

Second attempt

 (2.1)

 (2.2)

 (2.3)

 (2.4)

 (2.5)

 (2.6)

On my first attempt, expression (1.7) is almost fine, but β is supposed to be constant (and a function of "t" in the future), so I set it as a constant function. But then it causes that problem. Therefore, on my second attempt, I tried to set β as a parameter since the beginning, but it was no good either.

If I were to take the covariant derivative as "D_[nu](b[mu])" (without the "(X)"), it would not have that specific problem, but would not be a good solution, since the covariant derivative would discard the partial derivative of b[mu] and, if it would have some dependence on the coordinates, it would give a wrong result.

The only way it seems to work is by defining the tensor "Db[mu,nu]" explicitly as "d_[mu](b[nu](X)) - Christoffel[~alpha, mu, nu]*b[alpha]". (It seems that the problem comes from that "(X)" next to "b[alpha]" in the connection term.) But that would be an awful way to circumvent the problem. Isn't there any better way to get this?

Can someone help me with this, please?

Thanks for any help!

## How do I Drag+Drop PNG to Maple Worksheet without ...

How can add a PNG within a text section of a Maple Worksheet without having the image appear with a black background?

Does Maple have an alpha channel or transparency setting that must be toggled for this to work?

Maple 2019
macOS 10.14.6

I am added pictures from the clipboard via drag+drop.

(Yes, I know that I can use JPEG without this problem and that is NOT my question).

--
JJW

## Error, (in dsolve/numeric/BVPSolve) argument #4, t...

Hi everyone, I have a problem in the code solving coupled partial differential equations. I could not find out the solution. Please help me out with this. Find the code in the attachment.

## Is there something similar to solve/identity for d...

Hello,

I am solving some overdetermined system of ODEs in cylindrical coordinates r,phi,Z. I obtain some equations of the following type:

`(diff(_F1(phi, Z), phi)*r + diff(diff(s_r(phi, Z), phi), phi))/r = -s_r(phi, Z)/r`

As can be seen, the differentiated functions do not depend on r, which is an independent variable. Thus, the correct solution is to separate the equation and have

`_F1(phi,Z)=_F1(Z), s_r(phi,Z)=s_r(Z).`

By using dsolve, I always obtain a solution containing r.

A similar problem that does no contain derivatives is solved by solve/identity.

Is there something similar for dsolve?

EDIT: I again put here more info and file. I solve some overdetermined system of differential equations.

```[diff(s_r(r, phi, Z), r) = 0, diff(s_r(r, phi, Z), phi) = -diff(s_phi(r, phi, Z), r)*r^2,
diff(s_Z(r, phi, Z), r) = -diff(s_r(r, phi, Z), Z), diff(s_phi(r, phi, Z), phi) = -s_r(r, phi, Z)/r,
diff(s_Z(r, phi, Z), phi) = -diff(s_phi(r, phi, Z), Z)*r^2, diff(s_Z(r, phi, Z), Z) = 0,
diff(m(r, phi, Z), r) = s_Z(r, phi, Z)*B_phi(r, phi, Z) - s_phi(r, phi, Z)*B_Z(r, phi, Z),
diff(m(r, phi, Z), phi) = s_r(r, phi, Z)*B_Z(r, phi, Z) - s_Z(r, phi, Z)*B_r(r, phi, Z),
diff(m(r, phi, Z), Z) = s_phi(r, phi, Z)*B_r(r, phi, Z) - s_r(r, phi, Z)*B_phi(r, phi, Z),
s_r(r, phi, Z)*diff(W(r, phi, Z), r) + s_phi(r, phi, Z)*diff(W(r, phi, Z), phi) +
s_Z(r, phi, Z)*diff(W(r, phi, Z), Z) = 0]```

After some time, I arrive at the equation in the original question. So the independance of the other functions on r is the consequence of the other equations.

Here is the file (shortened): mwquestion2.mw

## File->Exit (Alt-F4) does not work in 2019.2 ...

This is another problem I just found in Maple 2019.2 on windows 10. professional.

I wanted to close Maple, so did  File->Exit

But Maple did nothing. It did not close.  Also Alt-F4 did not close Maple. I had to click on the little X on top right corner of the open window to close Maple.

In earlier version this used to work to close Maple.

Do others see this as well?  To reproduce, simply start Maple, and do File->Exit.

Here is a movie also

## Graph window dragging bug...

This may be a bug.  In Maple 2019.0

plot3d(x^2+y^2)

Now grab the graphing window and drag to adjust it's size.  It doesn't adjust it's size until you let go of the mouse button.

## very serious problem after upgrading to 2019.2. Re...

After upgrading to 2019.2 (on windows 10, 64 bit) using the pull down menu option I noticed the following problem.

I create a new worksheet and run it. Here is an example

```restart;

for i from 1 to 10 do
print(i);
od;
```

(the restart is on seperate cell).

It runs OK first time. I close Maple. Restart Maple again, open the same worksheet. Now once I evaluate the restart; command, the kernel crashes. This happens each time.

Any suggestions what to do?  Only fix I found is to copy the content of the worksheet and create a new worksheet, then it runs. But then the new worksheet fails again when I close Maple and restart again. So this is not a solution.

I also noticed it crashes ONLY when running the restart; command/cell. Other commands work OK. So something to do with initialization. I have not changed anything at all on my end after upgrading to 2019.2 from 2019.1.

Evaluating the next cell first thing when opening the worksheet, then it runs OK and no crash.

This only started to happen after updating to Maple 2019.2. No problem with 2019.1. Clearly this version was not well tested.  How could one revert back to 2019.1 ??

To answer comment below. It also happens in document mode:

## Change of the way init files are read in Maple2019...

I have a .mapleinit file that amongst other things sets libname so my own packages are accessible and can be loaded using with(). Imagine my surprise when I found that a maple program that ran half an hour ago on Maple2019 bombed when it did not find its package. Closer investigation indicates that maybe .mapleinit is only searched for in currentdir()??

The updated Maple is `Maple 2019.2, APPLE UNIVERSAL OSX, Oct 30 2019, Build ID 1430966`

The old one is gone :-(. It was Maple2019.0. I should add that on this system, Maple is installed on an administrator account that is not my user account (luckily I have access to that). I am running macOS 10.14.6 Mojave.

I verified my older Maples still work as before.

Has anyone else seen this behaviour?

Mac Dude.

Edit: I need to be more specific here: When I double-click a worksheet (.mw file) then currentdir() will be set to the directory the .mw file is in. This has been long-standing Maple behaviour. But then currentdir() does not cover the home directory where .mapleinit sits. As a result, a blank sheet finds my .mapleinit whereas my files (that habitually I open with double-click or drag-drop) do no longer run the .mapleinit file.

## Error, when trying to remove a task......

Hello people :)

As the captian says, im trying to remove an old task i've made.
But i get this:

Error in Get, invalid object [_XML_reply_data_get("reference" =
"_Maplets_reference_12","parameter" =
"#xa6","tning"))]

And i have no idea what it is, but it won't erase my task :'D

Have a great weekend you all
Best regards Lucas :)

## 2019.1 Help freezes whole computer...

A few seconds after calling up Help starts zucking araound and the whole computer then freezes. Ctrl-Alt-Delete doesn't work, hard reset required. Very funny. Am I alone?

## How to get all n nodes(n<=15) Non-isomorphic  conn...

I'd like to get all at most 15 vertices Non-isomorphic  connected  bipartite graphs. One way is to use the function NonIsomorphicGraphs(k, output = graphs, outputform = graph, restrictto = connected).

`with(GraphTheory):`

```k:=8; s1:=[NonIsomorphicGraphs(k,restrictto = connected,output=graphs,outputform=graph)]: bipartitegraph:=select[flatten](x->IsBipartite(x)=true, s1): nops(bipartitegraph);```
But when k=9, it is slow, I doubted that the code

By Checking out the encyclopedia，http://oeis.org/A033995 , we knew the following number of bipartite graphs datas of , at most 14, they are not many（the datas contain  no-connected conditions)

awesome.

Ps： I know  in SageMath  we can get all bipartite graphs quikly even though n>=10  by  using the

for g in graphs.nauty_geng('-c -b 10 -g'):

But I hope it can be realized in Maple.

Thanks!

## Probllem with member() and table()...

1. The member() function doesn't find the value in a table if that value is associated with the key (aka index)  '0'
2. Doesn't seem to matter if the table is created explicitly (ie by calling table()) or implicitly (ie by simple indexed assignment)
3. member() doesn't seem to have the same issue with a zero-based Array()
4. I'm pretty sure that this is a bug, but I'd like some opinions before I report it
5. This behaviour has been around for a while: same thing happens all the way back to Maple 18. (I can't check anything earlier)

Check the ouput of member(10,t1) in the attached

 > restart:
 > interface(version);
 (1)
 > # # Explicit table creation: same thing # happens if table is created "implicitly" #   t1:=table([0=10, 1=12]);   member(10,t1);   member(12,t1);
 (2)
 > # # Zero-based Array #   A:=Array(0..1, [10, 12]);   member(10,A);   member(12,A);
 (3)
 >

## Are these bugs of maple 2019? ...

Hello people in mapleprimes,
I have a question.

I use maple2019 with mac os 10.14.6.

```\$ sw_vers
ProductName:	Mac OS X
ProductVersion:	10.14.6
BuildVersion:	18G95```

With maple2019, errors appears.

```> kernelopts(version);
Maple 2019.1, APPLE UNIVERSAL OSX, Jun 6 2019, Build ID 1403154

> assume(a>-1,b>0);
Originally a, renamed a~:
is assumed to be: FAIL

> assume(tau<1,tau>0,s<1,s>0):
> a_e1:=tau*s*(1+tau)<tau*s+tau+s-1:
> b_e2:=expand(lhs(a_e1)-rhs(a_e1))<0:
>  b_e3:=collect(b_e2,s,factor):
> solve(b_e2,s) assuming tau<1;
Error, (in assuming) when calling 'property/ConvertProperty'. Received: 'FAIL
is an invalid property'```

On the other hand, with maple2018, they do not.

```> kernelopts(version);
Maple 2018.2, APPLE UNIVERSAL OSX, Nov 16 2018, Build ID 1362973

> assume(a>-1,b>0);
Originally a, renamed a~:
is assumed to be: RealRange(Open(-1),1)

> assume(tau<1,tau>0,s<1,s>0):
> a_e1:=tau*s*(1+tau)<tau*s+tau+s-1:
> b_e2:=expand(lhs(a_e1)-rhs(a_e1))<0:
> b_e3:=collect(b_e2,s,factor):
> solve(b_e2,s) assuming tau<1;
1
[{-------- < s~}]
1 + tau~```

Are errors due to some bugs in maple2019 when being used with mac os 10.14.6?

Take care.

taro