Bonjour,

Comment écrire les composantes d'un vecteur contravariant avec des indices numériques ? Ce vecteur n'est pas un spacetimevector.

Par exemple : <x^1, x^2,x^3> avec cette écriture maple interprète ces indices comme des nombres et non comme des symboles

Merci pour vore retour

I do a calculation o a simple integral

      int(cosh(cos(2*t)), t = 0 .. 2*Pi)

and get the answer 0 (zero), which I know is incorrect. The cosh function of a real argument is always positive.

If I represent the cosh function as a sum of two exponentials

(1/2)*(int(cosh(cos(2*t)), t = 0 .. 2*Pi) + int(cosh(-cos(2*t)), t = 0 .. 2*Pi))

I get    

2*Pi*BesselI(0, 1)

which looks much better.

What's the matter? Why Maple yields two different results? Victor.

Hello, Probably there is a way to do this easily but I do not quickly find it within the help.

I want

rand(0..1)

to give a true! random number and not always the same number; otherwise it should be called

predefinedlist()

Seed is deprecated, not sure it would help though. So how do I go abouts?

I went to save a file in Maple and it had large amounts of calculated data. 

Maple didn't ask me if I also wanted to save that data like it usually does - it just saved it.  Saved a 13Mb worksheet that took 5 minutes to relinquish control on my laptop. 

The function evalf(  ) will encounter a critical bug when doing the following evaluation:

restart;
P1 := 1007;
P2 := 1014;
P3 := 1014.1;
evalf(P2 - P1, 2);
evalf(P3 - P1, 2);

The first evalf( ) returns a correct value, while the second one returns a wrong value.
This is really unbelievable!

hello,

How I can remove this error for dsolve equation.

Thanks

2023.mw

Download 2023.mw

how I can gain a function that it is fitting in these data in x and y and z?

please see the following figure.

this curve is a 3D diagram in three coordinates x,y and z.

Thanks

PLOTfitting.xls

Here we simulate the motion of a container with a flat bottom that can slide on a horizontal surface subject to dry friction (Coulomb friction).  Installed inside the container is an ordinary mass/spring/damper system where the mass slides horizontally.  We impart an initial velocity to the container.  That sets the mass into motion which then affects the container's motion.  Under certain conditions the container will undergo a stick-slip motion which is evident in the simulation.

This simulation very roughly approximates the motion of a partially filled bucket of water that slides on the floor when kicked.  The idea arose in a discussoin with Carl Love and mmcdara:
https://www.mapleprimes.com/posts/211677-Mass-Spring-Conveyor-Belt-And-Dry-Friction

In the animation below, the container is shown in dark color when it slides against the floor, and light color when it sticks.

Worksheet: slosh.mw

Hello people in mapleprimes,

I could modify an expression e_n_1b to simpler e_n_1e as is in attached file.
Is there any other way to change e_n_1b into e_n_1e?

Dec_22.mw

Thank you in advance.

taro

Here is an animation of a mass-spring system where the mass slides horizontally on a steadily moving conveyor belt.

The contact between the block of mass and the belt is of the dry friction kind (Coulomb's friction). Consequently the block periodically sticks to the belt and moves forward with it until the force of the stretching spring overcomes the force of friction and yanks it back, making it to slip against the belt. In the animation the block is shown in a dark color while slipping, and a light color while sticking.

The fully executed Maple worksheet can be slow to load and requires a good deal of memory. Therefore I have attached two versions which are identical in all respects except that in one of them I have removed the Maple output to make is easy to load if your computer has limitations.

Download worksheet (no Maple output) block-sliding-on-conveyor-belt-stripped.mw

Doiwnload worksheet (with Maple output) (sorry, exceeds MaplePrime's size limit)

Hello,

I have the following expression

Ve*k21*ke*x1+Ve*k21*x1^2+k12*ke^2*x1[t]+2*k12*ke*x1*x1[t]+k12*x1^2*x1[t]+k21*ke
^2*x1[t]+2*k21*ke*x1*x1[t]+k21*x1^2*x1[t]+Ve*ke*x1[t]+ke^2*x1[t,t]+2*ke*x1*x1[t
,t]+x1^2*x1[t,t]

and I want to convert it to

x1[t,t]*(x1+ke)^2+(k12+k21)*x1[t]*(x1+ke)^2+Ve*x1[t]*ke+(k21*Ve)*x1*(x1+ke)

How can I do this opperation? This is just a simple example of a more general problem I am facing. Thanks in advance for your help

In graph theory, the crossing number cr(G) of a graph G is the lowest number of edge crossings of a plane drawing of the graph G. I'd like to use maple to compute crossing number of some graphs (any graphs is ok,  for example： cr(K5)=1 ). Someone can help me ? thanks. 

I know the problem of computing the crossing number is NP, but I guess we have some good  ways to compute in some small graphs.

Hello,

Since I installed Maple 2019 in my new iMac with Catalina, I can't make it work properly.

1. Once open, it's impossible to shut it down. I always have to force its exit.

2. The context panel doesn't seem to work properly. It never shows the actions that it sould do.

3. It doesn't flow as the old Maple I use to have in my old iMac.

I've been looking for this issue both in this forum and in the whole internet, as well as sending messages to technical support, and still can't find any answers. If someone knows something, plese let me know.

Kind regards,

Fermat66 

I want to factor large numbers, for this purpose I want to utilize multi cores on my computer.

Anyone who can help me in solving this problem?

I am utilizing Lenovo Thinkpad T440s with specifications core i7-4600 CPU @ 2.19 GHz.

In addition I would like to ask if anyone can help me in integrating GPU's with Maplesoft 2019 for factorization.

I am having a cluster of 64 GPU's i.e. AMD RX-460.

Any help in this regard will be appreciated.

Hello people in Mapleprimes,

A long time has passed since I came here before.
I have forgotten a lot of what I remembered about maple.

I want to incert gamma from e_nsp1 and (1-gamma) from e_nsp2 into set_3, so deleting gamma and (1-gamma) from set_3.
How can I do this?

Thank you in advance.

Take care.

question_1.mw

taro