I want to solve for the intrinsic frequency of a structure by using the equation of the determinant of a matrix equal to 0. I don't know if this is the correct procedure. Also the result is too complicated, what does z mean? Is it possible to simplify the result?

odeadvisor says that this ode is _homogeneous, `class A`, but I am not able to verify this. Also when asking dsolve to solve it as 'homogeneous' it returns no solution. 

This type is described in https://www.maplesoft.com/support/help/maple/view.aspx?path=odeadvisor%2fhomogeneous

Here is worksheet with my tries.

Would someone be able to confirm if this is really an _homogeneous, `class A` ?

my own code checking says no.  But if it is, then why dsolve do not solve it when asking it to use homogeneous method? Is the method I asked it to use it do not apply to class A?

Download checking_homogo_ode_type_june_18_2024.mw

Hi everyone...
if f(x,y)=x+y
How can I calculate the following expressions for derivative of y(i) where i=1...n?

Hello guys, I am doing the numercial error analysis study, but now I meet such problem:
how to change the 2d dot plot to the 3d plot? I mean extending like the generatrix of a cylinder.
It can be understood as the inverse operation of projecting a three-dimensional xyz surface onto the xy plane. the code is attached. Welcome all you discuss.

Dear all, how can I plot the edge coordinates of a 2d plane?

We are happy to announce another Maple Conference to be held October 24 and 25, 2024!

It will be a free virtual event again this year, and it will be an excellent opportunity to meet other members of the Maple community and get the latest news about our products. More importantly, it's a chance for you to share the work you've been doing with Maple and Maple Learn. 

We have just opened the Call for Participation. We are inviting submissions of presentation proposals on a range of topics related to Maple, including Maple in education, algorithms and software, and applications. We also encourage submission of proposals related to Maple Learn. 

You can find more information about the themes of the conference and how to submit a presentation proposal at the Call for Participation page. Applications are due July 17, 2024.

Presenters will have the option to submit papers and articles to a special Maple Conference issue of the Maple Transactions journal after the conference.

Registration for attending the conference will open in July.  Watch for further announcements in the coming weeks.

I encourage all of you here in the Maple Primes community to consider joining us for this event, whether as a presenter or an attendee!

Kaska Kowalska
Contributed Program Co-Chair

using diff command to find  partial dervative of function g give zero in maple...it shouldn't be zero...how to fix itpartial_dervative.mw

Download partial_dervative.mw

if i want to solve non linear least square problem ..maple optimazation Interactive box show ..many option...but when it comes to least square default....what kind of algothrim does it used....and in maple ..NonLinear fit commad use what kind of algothrim?..Levenberg-Marquardt algorithm?

I use one engine per one worksheet. So one would expect that doing restart; command; to always behave the same way. Right?

Because each time, new or refreshed mserver.exe is used.  But here is a worksheet, where I run it few times (all with restart each time), where sometime the command timelimit hangs, and sometime does not. I do not mean it takes little longer sometime. I mean completely hang.

I've waited 10-20 minutes and nothing happens. And sometime I saw it return back in 2 or 3 minutes. But most of the time it hangs.

I wish someone could explain this to me. If it hangs each time, or not hang each time, I can understand. (ofcourse timelimit should never hang, as it was supposed to have been fixed in 2021, but this is separate issue).

But why it hangs sometimes and not other times? Does Maple use some sort of random number generator inside it to decide on things? For me, software should behave the same each time when run from same initial state.

It also depends on the amount of timeout given if it hangs or not.

What can cause this different behavior and most important, what can one do to make it behave same way each time? I thought that what restart supposed to do.

Any insight what can cause this is welcome.

I also found that closing the worksheet completely and opening it again, results in different behavior in the timing. It looks like restart does not clear everything, as what happens when closing the worksheet and reopeing it again.

i.e. Sometimes when it completes and not hang, then issuing restart again and running the int() command, it will also not hang most likely.

It seems Maple have remembered something. But closing the worksheet and opening it again, it will hang again most of the times.

The point of all this, is that Maple behaves differently each time. But why??

Download hangs_int_june_16_2024.mw

Here is one screen shot of one of those times where it returned back. Took little over one minute. Good.

Here is second screen shot where it took about1,800 real time seconds to return. (30 minutes, even though timelimit was one minute). Same exact code.

update

I tried the suggestion given below to use _EnvProbabilistic:=0 but it had no effect on making Maple behavior consistent each time.

Below worksheet shows this. I tried 6 trials, each with restart. 

First trial it timeout at 74 second. good. Second trial took 1403 seconds !  Third trial went back to 74 seconds again (good).  Trial 4 took also took about 74 seconds (good). trial 5 went back to being slow and took about 1400 seconds again. Trial 6 went back to being fast and took about 74 seconds.

So the pattern seems to be 

                     fast SLOW fast fast SLOW fast.....

But I also tried this whole test again, by closing the worksheet and opening. Now the pattern changed to

                     SLOW fast fast fast SLOW SLOW ....

I also attached the worksheet for the above below.

So Maple still behaves in random fashion in doing the integration above. sometimes it is slow, sometimes fast. All using same exact code and same integral. Extra points to anyone who could find out why and how to fix this.  

This worksheet have pattern    fast SLOW fast fast SLOW fast....

Download hangs_int_V2_june_16_2024.mw

This worksheet below have pattern      SLOW fast fast fast SLOW SLOW ....

Download hangs_int_V3_june_16_2024.mw

Observation: When it finishes fast, timeout is always in  PDEtools/NumerDenom.

When it takes long time, timeout is always in sdmp:-mull

Any other suggestions what to try are welcome.

expr:=cos(x)^2;
expr=combine[trig](expr);
(x->x=combine[trig])(expr);

Update:
Same outcome with

expr=`combine/trig`(expr);
(x->x=`combine/trig`)(expr);
                          2   1            1
                    cos(x)  = - cos(2 x) + -
                              2            2

                           2               
                     cos(x)  = combine/trig

Hi everyone ...

How can I define the below Matrix with for command: (A[n] is n*n and n=1...i)

Tnx...

It seems like there exists a bug when taking the following limit in Maple (I tried Maple 2021):

If I run this command:
> evalf(limit(CylinderU(0,CylinderU(0,x)),x=0));
1.2722774800
the result is 1.2722774800, which seems to be incorrect.
;

However, when I run this command:
> evalf(CylinderU(0,limit(CylinderU(0,x),x=0)));
0.5456799403
the result is 0.5456799403, which seems to be correct.

Finally, when I run this command:
> evalf(CylinderU(0,CylinderU(0,0)));
0.5456799403
the result is 0.5456799403 which is also correct.

My expectation is that all three commands must return the same result, thus I consider this a bug.
I also run the following command in WolframAlpha
> limit ParabolicCylinderU(0,ParabolicCylinderU(0,x)) as x->0.0
and obtained the correct result 0.54568, confirming that in Maple this is evaluated incorrectly.

Would appreciate if anybody can confirm that this is a bug.

How such Maple bug should be reported?

Is this a valid behvior by int?   

int(A,x,method=_RETURNVERBOSE) hangs.

But  int(simplify(A),x,method=_RETURNVERBOSE) returns in few seconds with "default" result same as int(A,x)

Should this have happen? I try to avoid calling simplify unless neccessary because it can add csgn's and signums and so on to the result. 

But the question is: Should one really need to simplify the integrand to get the result in this example? Does this mean one should call simplify on the integrand to avoid the hang that can show up? 

This only happens when using method=_RETURNVERBOSE 

Just trying to find out if this is normal behavior and can be expected sometimes.

Download why_int_hang_unless_simplify_june_15_2024.mw

How do you substitute into a contravariant index of a tensor say

T[~mu, nu]     ?

Nothing seems to work, I tried to subs(~mu=~1,T[~mu, nu]), subs(mu=1,T[~mu, nu]), and all permutations.

Substituting values into the covariant index works fine but not contravariant.

Surely it must be possible ?