I've been evaluating Grid but I found some problems with SQLite DB when not using numnodes.

So I am now using numnodes option to setup explicitly number of nodes to use with Grid.

But the problem is now print() do not show on the screen from node code. So hard to debug. So I changed code to send debug messages to print files.

But now I find that the files do even get created when using numnodes. 

When removing numnodes option, the text file gets created. 

I am using FileTools:-Text:-WriteString() and FileTools:-Text:-Close() in the node code.
I also tried using fopen(). Both do not work. 

Same code works OK if I do not use numnodes. 

Any idea why the file do not get created when using numnodes? Worksheet to produce this is below.

I use C:\\tmp folder for testing. Feel free to change this. When I run the code and look in the folder, I do not see the text file there when using numnodes. 

It is possible the file is created but saved somewhere else on the system even though the full file name is given?

It seems to me now that when using numnodes option, there are some things that work and some things that do not work. I do not know if this is by design or a bug. Any one knows?

Download grid_question_jan_29_2025.mw

To see the file 0_file.txt get created in the folder, simply remove the numnodes option.

Dear all,

I'm a new maple user trying to solve a single PDE in maple using finite volume.

For simplicity I'm using three volumes. When I'm trying to apply a simple flux limiter, up-wind scheme, (relation between the wall and the node values u[j+0.5](t)=u[j](t)), I'm solver works well and produces accurate results.

However, when I try to a more complicated flux limiter, the solver doesn't initialize and I'm getting an error:
"Error, (in dsolve/numeric/DAE/make_proc) specified dependent variables [u[0](t), u[.5](t), u[1](t), u[1.5](t), u[2](t), u[2.5](t), u[3](t), u[3.5](t), u[4](t)] do not agree with input system {u[0], u[1], u[2], u[3], u[4], u[1/2], u[1.5], u[2.5], u[3.5]}, differences: {u[1/2]}, {u[.5]}".

I would greatly appreciate it if somebody helps me on in this issue.

error.mw

in a lot of my equation i have such problem and really i don't know how fix this also i try to put : in end and sometime is work and i keep contionues  but sometime not there is any way for solve this problem?

limit.mw

i don't know how generate this series and when i have a lot series which i can't make them automatically i don't know how write and replacing some structure like mu is zero or 1 as shown in picture can any one give me a hand?

both of them are same with little different

i need find parameter in explicite way without Rootof() so i need use code of explicite but i get error but when i use all parameter without explicite all parameter come out so why i get this error?

zero.mw

It's 2024 and this is still something that doesn't exist? I'd just like to swap the Enter/Shfit+Enter behaviors since I find myself writing a lot of multi-line and custom procs and boy howdy it'd be nice if I could make Maple behave at least the littllest bit like, I dunno, every other product I own and use.

Just around a month after the first release I am glad to announce the second public release of this project.

Changes from last release:

• added angled cuts to beam ends
• fixed bug for bolt connections with thick steel plates
• rewrite check if fasteners are placed within beams
• removed some obsolete procedures in NODEFunctions
• minor changes in XML file headers

For more information see https://github.com/Anthrazit68/NODEMaple.

i found solution of PDE but there is some different from my solution and paper solution so there is must be a mistake becuase he solved by maple too he mentioned in the paper i try to figure out but i can't see any mistake from my solution can anyone watch where i did mistake, i change some letter in finding parameter but they are same like p=k&h=A&n=p&w=n

here is paper solution 

parameter-different.mw

I was trying to look for an easy way to plot the locations of the distance and midpoint on a graph. I found how to get the distance and midpoint functions but plotting them is hard.

Thanks in advance.

Download How-to-plot-distance-midpoint.mw

i want to plot density i try to use code of [interactive] but didn't give me density 

>  >  Warning, A new binding for the name `gamma` has been created. The global instance of this name is still accessible using the :- prefix, :-`gamma`.  See ?protect for details.   >  >  >  >  {x, y, a[0], k[2], p[1], p[2]}   >  P :=   [  a[0]=1.2, k[2]=0.8, p[1]=-0.8, p[2]=0.4] (1) >  latex(P) [a_{0} =  1.2, k_{2} =  0.8, p_{1} = - 0.8, p_{2} =  0.4]   >  Assume some functional form for U(xi) >    insert numerical values >  solnum :=subs(P, sol3); (2) >  cg0 = 0.3200000000e1 / ((0.4000000000e0 * x - 0.8e0 * y) ^ 2 + (0.8e0 * x + 0.4e0 * y) ^ 2 + 0.12e1) - 0.5120000000e1 * x ^ 2 / ((0.4000000000e0 * x - 0.8e0 * y) ^ 2 + (0.8e0 * x + 0.4e0 * y) ^ 2 + 0.12e1) ^ 2;   >    >  >  >  Warning, expecting only range variables [x, y] in expression density(3.200000000/((.4000000000*x-.8*y)^2+(.8*x+.4*y)^2+1.2))+density(-5.120000000*x^2/((.4000000000*x-.8*y)^2+(.8*x+.4*y)^2+1.2)^2) to be plotted but found name density   Warning, expecting only range variables [x, y] in expression contour(3.200000000/((.4000000000*x-.8*y)^2+(.8*x+.4*y)^2+1.2))+contour(-5.120000000*x^2/((.4000000000*x-.8*y)^2+(.8*x+.4*y)^2+1.2)^2) to be plotted but found name contour

Download graph-density-countour.mw

Download F-params.mw

I first tried Threads and found that Maple dsolve does not work in threads (see https://www.mapleprimes.com/questions/239602-Error-in-Dsolve-Type-System-Does)

It was suggested there to use Grid instead of Threads. 

Now I got time to try Grid. My first test shows that Grid does not work with dsolve also.

Here is an example where dsolve solves this system of odes,. But when using Grid, Maple gives an internal error 

         Error, (in evalapply) cannot apply non-operator differential equation

Does this means one can't use Threads and also can't use Grid with dsolve? Or Am I doing something wrong?

This error happens on this specific ode. I tried 2-3 others and did not see an error. So it seems to depend to what the ode is.

Download dsolve_also_fail_in_grid.mw

in help for Grid:-Wait, it has an example where it says

And in help for Grid:-Setup it says

"The numnodes option allows you to specify the number of nodes to be used in subsequent computations.  This option is only available in "local" mode."

Is numnodes supposed to be the same as number of cores on my PC?  If so, then why numnodes=4 says this will insure it run run on 2 core machine?

Is this typo and it should be 4 core machine?

there is must be a problem but i didn't figure out ?  in this command didn't give me my parameter why?
vars1 := indets(eqs1);
ans := solve(eqs1, {a[0], a[1], a[2], a[3], a[4], e[1], k[1], n[1], p[1]});

parameter.mw

Download polar.mw