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

How i can find parameter after substitution in our pde 

Download N-soliton.mw

I want to calculate Hodge Star of forms on a solvable Lie algebra L, I have defined a metric tensor g on it. But when I use that g to compute the Hodge Star of an operator it tells me that the g is not a metric tensor.

with(DifferentialGeometry);
with(LieAlgebras);
A := Matrix(4, 4, [[A__11, A__12, A__13, A__14], [A__21, -A__11, A__23, A__24], [-A__24, -A__23, -A__11, A__21], [-A__14, -A__13, A__12, A__11]]);
x := [x__1, x__2, x__3, x__4, x__5, x__6];
StructureEquations := [[x[6], x[1]] = a*x[1], [x[6], x[2]] = add(A[1, i]*x[i + 1], i = 1 .. 4), [x[6], x[3]] = add(A[2, i]*x[i + 1], i = 1 .. 4), [x[6], x[4]] = add(A[3, i]*x[i + 1], i = 1 .. 4), [x[6], x[5]] = add(A[4, i]*x[i + 1], i = 1 .. 4)];
L := LieAlgebraData(StructureEquations, [x[1], x[2], x[3], x[4], x[5], x[6]], Alg1);
DGsetup(L);
with(Tensor);
e := [e1, e2, e3, e4, e5, e6];
theta := [theta1, theta2, theta3, theta4, theta5, theta6];
omega := evalDG(add(theta[i] &wedge theta[7 - i], i = 1 .. 3));
g := evalDG(add(theta[i] &t theta[7 - i], i = 1 .. 3));
HodgeStar(g, theta1)

It is showing the following error,

Error, (in DifferentialGeometry:-Tensor:-HodgeStar) expected 1st argument to be a metric tensor. Received: _DG([["tensor", Alg1, [["cov_bas", "cov_bas"], []]], [`...`]])

How can I correct this? If not is there an alternative of doing what I am trying to do?

i try to get same result by substituation but i don't know what is mistake after i take second derivative is wronge i don't know how get same result as in paper did can anyone help  to calculate this part is not hard but is complicated ,How calculated second derivative and put in our ode to get the parameters?

Download complex-issue.mw

How do I generate a plot within a plot as shown in my example below? The fundemental issue is plot structures like Histogram() etc are not images and so combining them in the way I imagine is non-trivial. I couldn't find a standard way to do this in the help section.

Plot_within_a_plot.mw

Download Plot_within_a_plot.mw

Is there an easy way to get the midpoint and distance in maple?

Thanks in advance.

Download 2.1-Distance_and_Midpoint.mw

Can maple simplify a Combined Inequality? At best it outputs imho a more complicated solution.

Thanks in Advance.

Download Combined_Inequality.mw

every thing is correct but i dont know why my PDE is not be zero, i did by another way is satidy but i change whole equation by sabstitutiin then i did ode test is satisfy by putting case in equation and solution with condition but when i want to use pdetest  test in pde is not satisfy ?

Download pdetest.mw

Is there something one can do to make Maple give same result each time? It seems all random.

Calling odetest sometimes gives internal error. 

            Error, (in trig/normal/sincosargs) too many levels of recursion

But it is random when and how it happens. Worksheet below shows that sometimes when adding infolevel[odetest]:=5; make the error go away. sometimes trying 2 or 3 times also makes the error go away.

This makes it impossible to reason about things, as sometimes I get different result using same exact code.

Is there something one can do to remove this internal error? Why it happens sometimes only?  Do I need to clear something before calling odetest to make sure same result is obtained each time?

Download why_odetest_sometimes_fail_internal.mw

Add tracelast; after an error gives long output with this at end

...
#(\`trig/normal\`,8): sincosargs := [\`trig/normal/sincosargs\`(a)];
 \`trig/normal/sincosargs\` called with arguments: ((-2472*2^(1/2)+3496)*3^(1/2)-4288*2^(1/2)+6064)*(10+7*2^(1/2))^(1/2)+(6008*6^(1/2)-8496*3^(1/2)+10408*2^(1/2)-14720)*cos((1/24)*Pi)
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: ((-2472*2^(1/2)+3496)*3^(1/2)-4288*2^(1/2)+6064)*(10+7*2^(1/2))^(1/2)
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: (-2472*2^(1/2)+3496)*3^(1/2)-4288*2^(1/2)+6064
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: (-2472*2^(1/2)+3496)*3^(1/2)
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: -2472*2^(1/2)+3496
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: -2472*2^(1/2)
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))

Not only is it random error, it also can not be cought using try/catch. So the whole program now stop and there is no way around it. If it was at least possible to trap the error, then it will not be a big deal. But when not even possible to trap Maple errors, then what is one to do? 

Update Jan 18, 2025

I did not want to make new post on this, even though the error is different, but it is similar issue to this post.

I found another example of this random failure of odetest using same input.  May be this will help Maplesoft find the cause. 

The internal error this time is Error, (in depends) too many levels of recursion

In this worksheet below. the same ode and 3 solutions were used. As you see, sometimes odetest do not generate internal error, and sometimes it does. All happen on 3rd call to odetest. 

So it is completely random why this happen. The first and 4ht tries generate no error, but the second and the third do. All were run after restart is called. So one would expect same output from each try,

Download bug_odetest_jan_18_2025.mw

Hello,

I present the result of work on a new project in the field of classical mechanics. It is a grateful and interesting topic that gives a lot of satisfaction. I am attaching the Maple worksheet.

Best regards

Rolling_Disk_3D_on_x0y_plane.mw

Hey guys,

I have to solve a bunch of systems of polynomial equations und dome restrictions given by inequalitites. I have 8 variables, 8 equations and and 13 inequalitites. Since the simple solve or SemiAlgebraic command are not able to solve every system I tryd some other ways. Right now I try to bring the set of equations and ineqaulities in a better from or structure using RealTriangulize from the RegularChains library. Later on I want to take those results and use solve or SemiAlgebraic again, hoping, that Maple than finds the solutions and is not calculating for houres without a result. I already know, that you can have diffrent outputs for RealTriangularize (I know list, record, piecewise and zerodimensional, althought the last one is not really helpful). Since I want to go on wirking with the results I need to have them in a form, that I can read of the new equations and inequalities to put them into solve. Often that works totaly fine, but sometimes I get an output I dont understand. I understand what It means but I dont understand why Maple uses that type of output. If you have a look in the attached file you can see what I mean:

I would like to get results like in dec_5334. I can easily go on working with this kind of form. In dec_5380 you can see a diffrent output. I dont see the point of giving me this output. the second line i basically epmty. and in the first line the solution is broken into peaces. when a certain solution just works under some inequalitites, why dont they put those four inequalities inside of the list in front of it? Is there a workaround for the "normal" output? Or is there a way to read off the lines from this kind of structure, with the open { in front ?

The same problem appears in dec_5382. WHy dont give me a list with to lists of equations and inequalities to show me both solutions?
In the last example dec_5382_record you can see the output when you change the corresponding option in RealTrinagularize. But here I again have the problem that I dont know how to read of the equations and inequalities from the open curly bracket.

If anyone could help me, I would be very glad. Thank yu in advance.

Regards

Felix

Download Output_of_RegularChains.mw