[Here's the original Question, restored as best I could.--Carl Love]

[The question was, of course, How to avoid the error?--Carl Love]

Download subgrouplattice_(1).mw

Hi

how to say 

i from 1 to 4 in maple

for example

if I have this eqauation

and I need to sub i in this equation to get 4 equation

Many thank

I'm trying to solve a beam vibration problem. I am relatively new to Maple and trying to solve PDE's. I feel like I'm pretty close, but I don't understand what's wrong here.

This is my maple file.

Thesis_Pde2_attempt.mw

as a note, I made some simplifying assumptions. I am just using part of this equation since it is less complex. And my boundary conditions are simply supported on both ends so no displacement and no 2nd derivative at the ends.

Any help would be greatly appreciated!!

Hi!

I have a problem recently with running RootFinding:-Isolate inside a procedure which is run on threads. I have many polynomial systems to treat so I would like to balance computations between cores. Unfortunately, my code always breaks computation kernel with the error:

java.lang.NullPointerException

at com.maplesoft.mathdoc.model.WmiModelLock.acquireLock(Unknown Source)
at com.maplesoft.mathdoc.model.WmiModelLock.writeLock(Unknown Source)
at com.maplesoft.worksheet.connection.WmiOutputUpdateBuffer$UpdateSynchronizer.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

I wrote a small example below

f:=proc(n)

   local i;

   for i from 1 to n do
    try

      RootFinding:-Isolate([a^2+b^2-1/3c^2,a^2-1/3b^2+c^2-1/3,a^2-1/3b^2-1/3c^2+1],[a,b,c]):

   catch "":
     next:
   end try:
  end do:
end proc:

Threads:-Task:-Start ( null, Task[f,10000], Task[f,10000], Task[f,10000]);

I have no much of experiences with threads in Maple so I would not be surprise if I'm trying to do something completely wrong here. Any hint or advice will be appreciate. 

hi,

having some issue using the codegeneration function in maple. I have a script written in Maple that I would like to do in Python 2.7. I knew to maple and not sure if my syntax is incorrect or if the program doesnt support the conversion, as an example,

thanks

Hello,

I would like to plot an non coupled non linear oscillator.

The equations are the following:

K:=Matrix([<0, -1, 1, -1>,<-1, 0, -1, 1>,<-1, 1, 0,-1>,<1, -1, -1,0>]);
omega[sw]:=beta/(1-beta)*omega[s];
for i to 4
do
r[i]:=sqrt((u[i](t)/(L/2))^2+(v[i](t)/H)^2):
omega[i]:=omega[st]/(1+exp(b*v[i](t)))+omega[sw]/(1+exp(-b*v[i](t))):
Equ[i]:=diff(u[i](t),t)=Au*(1-r[i]^2)*u[i](t)+omega[i]*(L/2)/H*v[i](t):
Eqv[i]:=diff(v[i](t),t)=Av*(1-r[i]^2)*v[i]+omega[i]*(L/2)/H*v[i](t)+MatrixVectorMultiply(K,<seq(v[i](t),i=1..4)>)[i]:
EqSys[i]:=[Equ[i],Eqv[i]]:
end do:

My parameters are the following:

paramsGeo:=L=0.015,H=0.015,beta=0.5,Vf=0.3;
omegaS:=eval(Pi*Vf/L, [paramsGeo]);
paramsCycle:=omega[s]=omegaS,Au=1,Av=1,b=100;
params:=paramsGeo,paramsCycle;

I'm not sure with my initial equations. But, may be it is possible to start with:

ic:=[u[1](0)=0.8, v[1](0)=0,u[2](0)=0.8, v[2](0)=0,u[3](0)=0.8, v[3](0)=0,u[4](0)=0.8, v[4](0)=0];

For these equations, I would like to obtain the following plots:
- plot 1: horizontal axis : u[1](t) vertical axis : v[1](t).
- plot 2: horizontal axis : u[2](t) vertical axis : v[2](t).
- plot 3: horizontal axis : u[3](t) vertical axis : v[3](t).
- plot 4: horizontal axis : u[4](t) vertical axis : v[4](t).
- plot 5: horizontal axis : t, vertical axis : v[1](t), v[2](t), v[3](t), v[4](t).

For this last plot, I would like to obtain this kind of curve:

I image that since my equations are coupled i can not use directly use Deplot function but Dsolve.

May you help me for defining a good syntax for solving my system and then deducing the following plots?

Thanks a lot for your help

guys,

how can i compute a tensorial term ( dAlembertian ,..) in anholonomic frame ?

On.mw

thanks in advance

Hello,

I would like to know how to do the following. If I received a plot of a graph, but I did not know it function, how could I get an accurate value for its maximum and minum points? Any help is greatly appreciated! Thank you in advance!

Kind regards,

Gambia Man

Hello everyone, 

I have some problems with the "isolve" command on Maple. I am trying to solve for integer a very easy system of equations. When I type the commands

restart; 

n := 2;
isolve({sum(a[k], k = 1 .. n)-1 = 1}, d)

I get the expected {a[1] = 2-d, a[2] = d}. However, if I add conditions a[1],a[2] >= 0, that is the commands

restart;
n := 2;
isolve({ge(a[1], 0), ge(a[2], 0), sum(a[k], k = 1 .. n)-1 = 1}, d)

I get the warning "Warning, solutions may have been lost". What am I doing wrong? Is there a way to get Maple to give me the possible values?

Thank you in advance,

David

I'm trying to solve a system of equations thats expressed as a summation (the original has the summation symbol as opposed to 'sum'):

d_actual := solve(W_actual = sum(W_guess(def-asp_rad_inverse[i], E, asp_rad[i]), i = 1 .. n), def);

When n<5, I get an answer after a few seconds, but when n is higher, the program sits and 'evaluates' forever...I've waited up to 30 min. 

Background:

I have a plate with a number of hemispheres on the surface (# of impacted hemispheres given a force = n). Each has a unique radius and they're listed from largest to smallest in 'asp_rad[]'. I have an equation for the deflection of a single hemisphere as a function of Force and material properties that I have rearranged with respect to Force (W_guess(deflection, E, r)). There's an opposing plate that stays parallel to the original plate while pushing down on the asperities with Force W_actual. The total deflection of the opposing plate is the sum of: 1) the difference between the tallest radius and the impacted radius in question (asp_rad_inverse[]), and 2) the deflection of the impacted radius in question. 

I'm attempting to solve for the total deflection of the opposing plate via solving for the 'def' in the summation above, but when I run it, the program is not able to compute a solution.

Thanks in advance.

Hello,

I'm a very new beginner, and I have a question about getting the data of a curve from a JPG, without using manual measures an too getting more accurate datas.

I wish to fit the curve with a model. The JPG joined, from EU 2015, is about human thermoregulation. I still try to found a model with Mathematica but am uncertain seeing the result as illogic.

Did anyone write something to read curves from a JPG and get coordinates from these curves ? In the JPG, the curve is above, as an 'U'.

Thanks for your advice,

Milos.

Hello,

I've been trying to collect points at certain intervals in my plot, however, the sample option doesn't seem to be working. Can anyone lend me a hand? Any help is greatly appreciated! Thank you in advance!

Kind regards,

Gam

Download Poincare_section.mw

bia Man

Hello,

I have a matrix K.

K:=Matrix([<0, -1, 1, -1>,<-1, 0, -1, 1>,<-1, 1, 0,-1>,<1, -1, -1,0>]);

I would like to program this operation :

May you help me to code this operation?

Thanks a lot for your help

Hello,

I have an error in my code. I don't know where it came from. Earlier today I loaded this and it worked fine and now an error comes up. Any help is greatly appreciated! Thank you in advance!

Kind regards,

Gambia Man

Download Poincare_section.mw

Hello!

If I type this into a CAS calculator from Texas, I get the right result for Uc wich is 545.2.

solve(Uc&angle;-90=400&angle;X-150&angle;0+j*174.4,Uc,X)

This is used in AC circuits.

However, in Maple I'm using polar coordinates, so Im using this preamble:

phasor := proc (r, theta) options operator, arrow; r*cos(convert(theta*degrees, radians))+I*r*sin(convert(theta*degrees, radians)) end proc

This basically means that I can write phasor(value,angle in degrees) and get the lenth and angle of a vector on the complex plane.

Basically I want to know how I can make Maple solve this:

evalf(solve({phasor(U__C, -90) = phasor(400, X)-phasor(150, 0)+phasor(174.4, 90)}, {Uc, X})) Where I'm just interested in U_C , X doesn't matter.

I can't figure out how to do this with my current preamble. Does anyone know how to make this work?