## 7596 Reputation

17 years, 160 days

## @Anthrazit That can be caused by a ...

@Anthrazit That can be caused by a disk that is about to fail.

## No direct way in Maple...

Maple is not equipped to handle numerical solutions of elliptic PDEs.  You may either write your own numerical solver -- that should not be very difficult if you know about finite differences -- or find another software that can do elliptic PDEs.

## What are you trying to solve?...

Long answer:  To get a more meaningful answer, you should post a more meaningful question.

## @Suryakanth The PDEs involve a deri...

@Suryakanth The PDEs involve a derivative of q2 but no boundary conditions on q2 are specified.

Suggestion:  Consider solving a few simpler problems to develop your understanding of how Maple works.  The problem that you are attempting to solve is much too difficult for a beginner.

## The error message is very clear:Error, (...

The error message is very clear:

Error, (in pdsolve/numeric/process_PDEs) number of dependent variables and number of PDE must be the same

That's because you are attempting to solve a system of six PDEs in seven unknowns.

## @Gabriel Barcellos For publication-...

@Gabriel Barcellos For publication-quality graphics, export the graphics as EPS (Encapsulated PostScript).  That produces vector graphics which may be included in a LaTeX document without a loss of quality.  If you need the graphics in the PDF format, apply an appropriate tool to convert the graphics from EPS to PDF.  Do not export directly from Maple to PDF as that embeds the graphics in a letter-sized (or A4) paper which is useless for further processing.   (This has been brought to Maplesoft's attention several times but the problem persists.)

Graphics posted on this web page are in the PNG format.  They are certainly not publication-quality graphics.

As to your question regarding the difference of quality between my version of the posted graphics versus yours, I don't see a detectable difference between the two graphics that you have posted other than the fonts of the tickmarks and labels.  As I noted in an earlier reply, that is done by specifying the font family and size, as in

```plots[setoptions](font=[TIMES,12], labelfont=[TIMES,16]);
plots[setoptions3d](font=[TIMES,12], labelfont=[TIMES,24]);```

You may include these in your Maple document—you actually need only the first one for 2D graphics—or you may put them in Maple's initialization file so that they apply to every graphics that you generate.

## Connected arrows...

@nm Yes, an option to draw connected arrows will be a good enhancement.  I don't see it as an option right now.

As to the font size, yes, I have it set in my ~/.mapleinit initialization file in Linux.  There should be something like that in Windows.  Here is what I have there:

```plots[setoptions](font=[TIMES,12], labelfont=[TIMES,16]);
plots[setoptions3d](font=[TIMES,12], labelfont=[TIMES,24]);
```

As to your question about DEtools:-DEplot versus DEtools:-phaseportrait, I always use the former.  DEtools:-phaseportrait seems to be redundant.

## Congratulations?...

@Suryakanth Considering that you started with "I am not familiar with maple", and then you wrote "I have not taken this worksheet from anywhere", I am impressed with the quality and sophistication of the code that you were able to create within a few hours after that.   It would take years for some people to reach that level of expertise.  Congratulations!

## without Physics!...

@acer I verified that the issue goes away after removing Physics from libname.

## @segfault The −j flag is...

@segfault The −j flag is not doucumented anywhere that I know of.  I found it in the script file bin/maple in Maple's installation directory.  I have no idea whether there is an upper limit to the heap size.

As to Maple 9.5, that goes back to almost 20 years ago and I have no access to it.  You may want have a look at the corresponding script file in your installation.

## Better grid...

@acer You are quite right, and the drawing looks better that way to boot.

## Vector versus list...

@MarcinM The documentation says that plots:-spacecurve takes a list or an rtable as an argument. A Vector is a special case of the rtable, so we are okay.

The documentation of plot3d says that the input should be a list.  The use of a Vector as input does not seem to be documented but that has worked for as long back as I can remember.

## Plotting vector functions...

@MarcinM Regarding "I do not understand the philosophy of plotting vector functions in Maple", you need to go back to Stewart's chapter 13 where space curves are introduced as vector-valued functions like this:
r(t) = < f(t), g(t), h(t) >
where t is a parameter.

The Maple command spacecurve( < f(t), g(t), h(t) > , t=a..b) plots that parametric curve.

But the parameter need not be named "t".  Any symbol may be used for the parameter.  In the answer that I posted, the parameter is named "x", as in:
C1 := < x, sqrt(1-x^2), 0>;

As to plotting surfaces in Maple, we do

plot3d([f(x,y), g(x,y), h(x,y)], x=a..b, y=c..d);

The parametric surface here is described as a list [f, g, h], but a vector description, as in <f,g,h> works just as well and produces the same result.  I used the vector representation in my answer.

## @simplevn1967 You referred to "...

@simplevn1967 You referred to "Maple 17".  Did you perhaps mean "Maple 2017"?  The two are quite different.   "Maple 17" was released in 2013 while  "Maple 2017" was released in 2017.

I ran the worksheet that you posted in my Maple 2017 and it worked just fine.  I don't have "Maple 17" on my machine so I cannot test it.  Perhaps "Maple 17" is too old for that code.

## Need the worksheet...

@simplevn1967 I cannot diagnose the problem without seeing your worksheet.

As you reply to this message, you will see a large green upward pointing arrow in the toolbar.  Click on it to attach your worksheet to your reply.

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