MaplePrimes - Maple 2020 Posts and Questions

How can this ode error message be avoided?

Earl — Sun, 23 Aug 2026 14:08:48 Z

The uploaded worksheet contains a second order ode with initial conditions which elicits an error message.
How can this error be avoided?

Bobs_sliding.mw

dsolve programming example

Earl — Tue, 07 Jul 2026 13:32:58 Z

The two uploads are my attempt to solve Problem 177 in the book "200 More Puzzling Physics Problems" by authors Peter Gnadig, Gyula Honyek and Mate Vigh.

The first upload of a conducting rod moving with initial velocity along two arms of a triangle in a perpendicular constant magnitic field successfully produces an animation.

The second upload of the rod moving on the arms of a parabola produces a puzzling error message when executing the ODE

What actual error in the ODE results in this error message?

What changes to the worksheet will result in successful execution of the ODE and a successful animation?

Rod_triangle.mw

Rod_parabola.mw

Where is this dsolve syntax documented?

Earl — Sat, 04 Jul 2026 19:50:14 Z

I cannot find a description of the use of the form of dsolve and the following evaluation of its constants which are found in the downloaded worksheet.

Gnadig_2_problem_177_Rod_moving_on_a_wire_in_B_field.mw

Animating the Dzhanibekov effect?

Earl — Tue, 16 Jun 2026 18:40:37 Z

The uploaded worksheet references two youtube videos.

The first one displays the animation of a simple device rotating about an axis tilted at a small angle from the device's principal axis having an intermediate moment of inertia.

The animation and accompanying verbal description demonstrate the Dzhanibekov effect.
The second video contains the first video's narrator's equations which produce the values used in creating the animation.

The uploaded worksheet contains my failed attempt to reproduce these values.

Please suggest the Maple 2020 compatible statements which correctly produce these values.

Dzhanibekov_effect.mw

Why is Threads:-Task:-Continue miscomputing?

RafalAblamowicz — Fri, 30 Jan 2026 06:53:17 Z

Hi,
I am experimenting with Threads:-Task:-Continue in Maple 2020.2 and sometimes it returns different results depending on N, or, how fine the mesh is. I have modified procedures cont and task in a Maple example shown in a worksheet. I can compare the result from Threads with one I can obtain another way and which surely is correct. The result from Threads depends on N: sometimes it is correct, sometimes it is not. The wrong result is returned only when the Threads:-Task:-Continue loop is executed, of course.

Has anyone spotted that problem? Is there a way to trace what actually is being done in each leaf? Does this problem appear in later versions of Maple?

I would appreciate some feedback.

Thanks in advance,

Rafal Anlamowicz
rablamowicz@gmail.com

Help with the Solution Steps?

delvin — Wed, 12 Mar 2025 12:33:55 Z

Hi,

In order to obtain an algebraic system, one must set the coeffcients of (H + G′/G2)i to zero. Solve the obtained algebraic system.

But the expressions were not arranged correctly, but no answer was obtained, while the answer was as follows:

restart

>	with(PDEtools): df:= diff(diff(G(xi), xi)/(G(xi)^2), xi)= A+B(diff(G(xi), xi)/(G(xi)^2))^2+ c(diff(G(xi), xi)/(G(xi)^2));

(1)

>	a := [a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10]:

>	p:= -2: q:= 2:

>	Y1 :=xi -> (add(a[i+3]*(H+(diff(G(xi), xi)/(G(xi)^2)))^i, i = p .. q)):

>	eq1 := -4(k^2)mdiff(Y1(xi), xi,xi) - 4l(Y1(xi)^2)+(4(nu^2)-4nun+n^2-4)*Y1(xi):

>	eq2:=subs(df,eq1);

(2)

>	simplify(eq2):

>	fin1:=simplify(numer(%)):

>	for i from 0 to degree(fin1,H+(diff(G(xi), xi)/(G(xi)^2))) do EQ[i]:=simplify(coeff(fin1,H+(diff(G(xi), xi)/(G(xi)^2)),i)); end do;

(3)

>	for i from 0 to degree(fin1,H+(diff(G(xi), xi)/(G(xi)^2))) do EQ[i]:=simplify(coeff(fin1,H+(diff(G(xi), xi)/(G(xi)^2)),i)); end do;

(4)

>	Eqs:={seq(EQ[i],i=0..12)}:

>	sol:=solve(Eqs,{a0, a1, a2, a3, a4, H, nu},explicit)

(5)

Download GGGGGGG2.mw