Unanswered Questions

This page lists MaplePrimes questions that have not yet received an answer

When I use Solve for a PDE with the option singsol=all, is Maple guaranteeing that I am getting all the solutions, and in partidcular , is it returning the *general* solution(s)? 

One of our users asks how they can find the Re ( sqrt(a+I*b)) where a, b are real.

They had tried entering the latter as "assume", without any luck. 

We told them that it may not be very intuitive, but such expressions can be evaluated by wrapping into evalc which implicitly assumes that free parameters are real-valued:

evalc(Re(sqrt(a+I*b)));

How is the matrix of the affinity of base the plan of equation x+2*y-z=1, of direction u <1,0,-1>and of ratio 2 determined? Thank you.

Hi,

I am trying to learn how to apply initial conditions to pdes with maple.  I have figured out how to do it with odes, but when assigning initial values to derivatives, I get weird results.  I have attached my Maple file, with the error, and a link to the document I am using as motivation for my analysis.

Test_1D_Wave_Equation.mw

https://personal.math.ubc.ca/~ward/teaching/m316/lecture21.pdf

I used to have this kind of code without problem:

myModule := module()
    option package;
    export myFunc;
    # local i;
    myFunc := proc()
        [seq(i, i in 1..10)]
    end proc;
end module;

But after upgrading to the latest version of Maple 2021, I get a warning

Warning, (in myModule:-myFunc) `i` is implicitly declared local |myModule.mpl:5|

I have to uncomment the local i declaration for the warning to go away. Has the behavior of seq changed in Maple 2021?

Maple returns to me an algebraic expression that involves many RootOf expressions and I have found it hard to get all solutions behind this expression (by using "allvalues") - this keeps on running without terminating. Is there a way to get the number of solutions without asking Maple to return all solutions explicitaly?

Dear Useres!

Hope everyone is fine here! I want to compare the coeficient of exp(k*eta[3]+m*eta[1]+n*eta[2]) for k=0,1,2,3,...,N,n=0,1,2,3,...,N and m=0,1,2,3,...,N for N=10 in the following attached file. But I got some error, please have a look and try to fix it as early as possible. Please take care and thanks

Compare_coeff.mw

Copying and Pasting of parameters (entered data) or text in text boxes does not work on my MapleSim 2021.1 Windows10 installation.

I tired the usual keys and context menus. Cutting works.

Thats what I get back when I paste text here after cutting

<math xmlns='http://www.w3.org/1998/Math/MathML'></math>

Copy&Paste of components works.  

Is this a known issue?

In mathematica, CommunityGraphPlot attempts to draw the vertices grouped into communities. 

g = Graph[{1 \[UndirectedEdge] 2, 2 \[UndirectedEdge] 3, 
   3 \[UndirectedEdge] 4, 1 \[UndirectedEdge] 4, 
   1 \[UndirectedEdge] 5, 5 \[UndirectedEdge] 6, 
   5 \[UndirectedEdge] 7, 7 \[UndirectedEdge] 8, 
   8 \[UndirectedEdge] 9, 7 \[UndirectedEdge] 9}, 
  VertexLabels -> "Name"];
ged = {{6, 7, 8, 9}, {5}, {1, 2, 3, 4}};# Gallai-Edmonds decomposition
CommunityGraphPlot[
 HighlightGraph[g, FindIndependentEdgeSet[g], 
  GraphHighlightStyle -> "Thick"], 
 Thread[Labeled[ged, {"D(g)", "A(g)", "C(g)"}]], PlotTheme -> "Web"]

This function is very useful, for example, if I get a partition of vertices, such as the gallai-Edmonds decomposition below, I use  CommunityGraphPlot to easily see the overall layout of the graph. I don't know if Maple has a corresponding function.

PS: The Gallai-Edmonds decomposition of a graph g is the partition {D(g),A(g),C(g)} of its vertices, where D(g) consists of every vertex v for which there exists a maximum matching of g that misses v, A(g) consists of every vertex v that is not in D(g) but neighbors some vertex in D(g) and C(g) consists of all remaining vertices.

Hi I have experienced another Maple 2021 error with those of my students who Maple 2021 Mac edition. 

Lets say their have saved a .mw on their main drive and tries to open the file from inside Maple. Maple gives an error like "file cannot be opened - please try to another". This also happens when trying to open the file from outside Maple. 

This never happens on the Windows version. So any idea what could be causing this ?

Hi. So my question is how can I get Square brackets on the phone app in calculations or is it possible?

 

 

I have the following expression.

Ps = (x - 600)(15000 + 400*(y - 4000)/2000 + 15000*0.40*(850 - x)/100) - y

Maple will evaluate this to:

Ps = (x - 600)(15000 + 400*(y - 4000)/2000 + 15000*0.40*(850 - x)/100) - y

Screenshot:

Plotting these two in 2D on Desmos to demonstrate: https://www.desmos.com/calculator/tvp4rbzxzp

These two are not the same expression. Is Maple broken or am I doing something wrong?

Hi,

I solve numerically an ODE system which depends on 25 parameters.
I want to know the maximum value of the time at which a specific event is triggered, when these parameters vary (independently the one of the other) within a 25 dimensional hyperbox.

To solve this maximization problem, which I assume is local1, I would like to use NLPSolve

The attached zip (I use Mac OSX) contains:

  • a file that gives a full description of the problem (the original ".pages" file and its export as pdf),
  • an m file wich contains the solution procedure plus a few other variables needed to solve the problem,
  • the mw file which contains:
    • the reading of the m file,
    • the procedure (OBJ) which returns the trigerring time,
    • many attemps to find its maximum value using NLPSolve.

None of my attempts at using NLPSolve gave me the expected answer

Could you help me to fix this?

Thanks in advance

mw_and_m_files.zip

1: Initializing a local method (see the explanation file) with different points gave me different optimizers but all of them led to rather close values of the objective function. Thus the problem is either global instead of local, or convergence might not be achieved for all the initialization points (but keep in mind that I'm not interested in the location of the minimizer(s) but in the maximum value of if the time when the event is triggered).

When I was drawing a plane graph, I found that the labels  of vertices were not displayed  and some edges even overlap when drawing because they were too close due to embedding.

restart:
with(GraphTheory):
g:=ConvertGraph("GsaCB{");
DrawPlanar(g,stylesheet=[vertexborder=false,vertexpadding=5,edgecolor = maroon,vertexcolor=gray,edgethickness=3])

So I thought that  option  Interactive  can adjust the position manually, but  at the same time I found that the style of  edges, such as the color and thickness, etc., is lost.  How to handle it? Is this a bug?

restart:
with(GraphTheory):
g:=ConvertGraph("GsaCB{");
DrawPlanar(g,stylesheet=[vertexborder=false,vertexpadding=5,edgecolor = maroon,vertexcolor=gray,edgethickness=3],layout=interactive)

I've written a Mapleflow document that is supposed to use a microphone array to find the intersection of three equations to locate the source of a gunshot.  But the calculation is "Evaluating," and has been for half an hour.  How do I interrupt the calculation?

I'd up load the file, but  

So: 

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