MaplePrimes - Maple 2020 Posts and Questions

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

Help with problems solving?

delvin — Fri, 07 Feb 2025 07:54:08 Z

Hello

I encountered a few problems. One is that in the first section, I wanted to use the definition above instead of f (s ) and g (s ), which means that when the variable changes under the integral sign, it should detect and replace it.

And the next is that in the Equality section, I should sort by p and set the coefficients to zero. And then, for example, solve for the zero power of p and get the value of f0 and use it in subsequent solutions. Can you help me?

>	restart; equ1:=diff(f(t),t)-1-t-t^2-g(t)-int(f(s)+g(s),s=0..t)=0; equ2:=diff(g(t),t)+1+t-f(t)+int(f(s)-g(s),s=0..t)=0;

(1)

>	f(t):=sum(f[i](t)*p^i,i=0..1);

(2)

>	g(t):=sum(g[i](t)*p^i,i=0..1);

(3)

>	hpm1:=(1-p)(diff(f(t),t)-1-t-t^2)+p(-diff(f(t),t)+1+t+t^2-g(t)-int(f(s)+g(s),s=0..t))=0; hpm2:=(1-p)(diff(g(t),t)+1+t)+p(diff(g(t),t)-1-t+f(t)-int(f(s)-g(s),s=0..t))=0;

(4)

>	A:=collect(hpm1,p);

(5)

>	for i from 0 to degree(A,p) do EQ[i]:=simplify(coeff(A,p,i)); end do;

Error, final value in for loop must be numeric or character

Download HPMsystem.mw

Can this theorem by proved?

Earl — Fri, 17 Jan 2025 17:56:28 Z

Problem Q15 in the book Parabolic Problems by David Angell and Thomas Britz describes a large circle (LC) and several smaller circles (SCs) which are each tangent to its neighbour SC(s), and externally to LC. All circles are tangent to the x axis and above it.

Section one of this worksheet displays the LC and six of the SCs based on the book's formula for the diameter of the latter in terms of the diameter of the LC and the largest SC, which is determined by the user.

Section two finds and displays that all of the displayed SCs' centers lie on the diameter of a circle closely related to the LC and larger than it.

Can this be proved to be the case for any sizes of the LC and SCs in the same formation as that displayed?

Parabola_Problems_Q15.mw

What is the correct way to solve these two problems?

Earl — Tue, 14 Jan 2025 20:05:00 Z

This worksheet defines two physics problems and fails in the attempt to solve the first one.

How can these problems be solved?

Rolling_circle.mw