Unanswered Questions

This page lists MaplePrimes questions that have not yet received an answer

To Maple support:

I was investigating this pde from a different forum.

I noticed that when using an expanded version of the pde, Maple hangs. Without expanding the PDE, Maple gives an answer in 2 seconds. 

Why does expanding the PDE makes a difference? I do not have an earlier version of Maple on my new PC to check if this is a new issue or not.
 

interface(version);

`Standard Worksheet Interface, Maple 2022.0, Windows 10, March 8 2022 Build ID 1599809`

Physics:-Version()

`The "Physics Updates" version in the MapleCloud is 1230 and is the same as the version installed in this computer, created 2022, April 21, 9:8 hours Pacific Time.`

restart;
pde1:=VectorCalculus:-Laplacian(u(r,theta),'polar'[r,theta]);
pde1_expanded:=expand(pde1);
bc  := u(1,theta)=sin(theta)^4,u(3,theta)=1;
pdsolve([pde1=0,bc],u(r,theta))
 

(diff(u(r, theta), r)+r*(diff(diff(u(r, theta), r), r))+(diff(diff(u(r, theta), theta), theta))/r)/r

(diff(u(r, theta), r))/r+diff(diff(u(r, theta), r), r)+(diff(diff(u(r, theta), theta), theta))/r^2

u(1, theta) = sin(theta)^4, u(3, theta) = 1

u(r, theta) = (1/52480)*((328*r^6-26568*r^2)*ln(3)*cos(2*theta)+(-r^8+6561)*ln(3)*cos(4*theta)+19680*(ln(3)+(5/3)*ln(r))*r^4)/(ln(3)*r^4)

pdsolve([pde1_expanded=0,bc],u(r,theta)); #HANGS, Waited more than 40 minutes.

 


 

Download hangs_pde.mw

Backspacing at the end of a few math containers on one row will shift them upwards beyond the top screen out of view and out of existence.  Your last chance of retrieval is when you can still see the bottom half portions of the letters/equations before you need to go to the first point and press enter to bring them down.  Once they're out of view, there's no chance to bring back what you wrote - the assignments are still valid.  Also note CRTL-Z will not bring them back. 

Using the hide command after displaying a plot in MapleFlow2022 prevents that plot from being moved.

If you create another plot, then both plots are movable until you use the hide command again, at which point you need to create another plot to allow plots to be positioned.

Let 
                              "a"

 and 
                              "b"

 be real numbers and 

       
"A = Matrix(3, 3, [[a, a - 1, -b], [a - 1, a, -b], [b, b, 2*a - 

   1]])"


,  
                              "B="


 "Matrix(5, 5, [[0, a, 3, 0, a], [3, 0, 0, b, 0], [0, 1, b, 0, 

    1], [b, 0, 0, 1, 0], [0, a, 1, 0, b]])"


(a) Show that if 
                            "0 <= a"


                            "a <= 1"

 and 
                      "b^2 = 2*a*(1 - a)"

, then A is an orthogonal matrix with determinant equal to one. 
(b) For what values of a and b is the matrix B singular? Determine the inverse of B (for those values of a and b for which B is invertible).
 

Find all rational function solutions to the Kadomtsev-Petviashvili equation 
                         
(&PartialD;)/(&PartialD;x);

diff(u, t) + 6*u*diff(u, x) + diff(u, x, x, x) - diff(u, y, y) = 0;

by u = 2 
diff(ln, x, x)*f;

=(2 (((&PartialD;)^2)/(&PartialD;x^2) f) f-2 ((&PartialD;)/(&PartialD;x) f)^2)/(f^2);
 with 
f;
  =
(a[1 ]x+a[2] y+a[3] t+a[4])^2+(a[5] x+ a[6] y+a[7] t+a[8])^2+a[9], ;
where 
a[i], i=1..9, ;
are real constants.
 

I am having a problem in evaluating a fluid flow problem at a boundary that includes infinity using a semi-analytic method Adomian Decomposition Method.

Find the attached code. Thanks in advance.

Just wondering how I do a loop over the contents of the table. I need both the index variable and the stored value associated with it.

This one apparently doesn't work.

F_vRk := table()

table( [ ] )

(1)

F_vRk["a"] := 1

1

(2)

F_vRk["b"] := 2

2

(3)

"for ind, val in F_vRk  do print(ind,val)  end do"

1, F_vRk

(4)

NULL

Download table_and_loop_1.mw

Hi everyone,

I'm new to using Maple and I've got a question concerning the calculation of the Lie Symmetries of an ODE. Basically, I want to us the method described in this paper: https://doi.org/10.1063/1.3097304 in order to find a perturbative solution to a system of first oder ODE's.

I thus need a special form of the generator. However I can't quite figure out the notation from the examples provided in the maple helt. I also can't figure out why I can't calculate the general form of the Symmetries using the following code: 

restart;
with(PDEtools);
with(DEtools);
Imp := 2*diff(y(x), x)*y(x)/A(x) - diff(y(x), x) - diff(A(x), x)*(y(x)/A(x))^2 - C_p*diff(A(x), x) - eta(x)*lambda(x)*sqrt(A(x)*pi)/4*(y(x)/A(x) - 1)^2 = 0;
Conti := diff(y(x), x) - 2*sqrt(A(x)*pi)*beta(x)*(1 - H + C/A(x)) = 0
Cons := diff(eta(x), x) = 0

sys := {Cons, Conti, Imp};
DepVars = {A(x), eta(x), y(x)};
deteqs := DeterminingPDE(sys);

Help or a link to some more examples would be much appreciated. 

Regards,

Johannes

hello,

I have 3 loops that I want to run, each loop runs a different procedure and have no interaction with the other, each loop takes about 5 hours to run so if I run the program in Series it takes about 15 hours, I can't separate the sheet into a few sheets and run it manually because there is initial data and calculations before the loops, so what I'm looking for is a way to parallel run these 3 loops.

The script I wrote so it would be clearer –

for i from 1 to n do 

for j from 1 to n do 

 x__Up[i,j]:= `Xmax__UP,m`(`P__m`(i,j),`I__m`(i,j),`data__upNc`);      

od:

if (i mod 10 =0 ) then  print(evalf((i)/(n))*100); fi:

od: 

for k from 1 to n do 

for m from 1 to n do 

 x__U[k,m]:= `Xmin__UP`(`P__m`(k,m),`I__m`(k,m),`data__upNc`);      

od:

if (k mod 10 =0 ) then  print(evalf((k)/(n))*100); fi:

od: 

Hii!!

I need your help in state space system.... kindly guide me how to solve State Space system in maplesoft.....i excecute the command but i didn't find the answer....can you plz help me?I have been trying for two weeks now but it is not working.Thank you!!

Hello, we need to do an integral based on two numerically approximated functions given by a second degree coupled differential equation.

The integral:
Where xs and xu are functions of the variable t.

We wish to do a half-sums to approximate the integral, that is:

Define an N = number of points, such that we get a delta_x = L/N.

We then wish to get two vectors x_s = [x_s(0),x_s(1),...,x_s(N)] and x_u = [x_u(0),x_u(1),...,x_u(N)] by running some kind of for loop over our approximation procedure.

Is there any function for this already inside of Maple? We need to approximate the integral using Riemann sums and no other method.

When trying to print a Maple Document as a PDF on Mac, I am now getting an "Error while printing" message. A 1-page pdf is created that's empty.   This is a new error, one that I've never seen when printing as PDF for any other Maple Document I've created.

I'm running Mac OS 12.3.1, the latest version of Mac OS and using Maple 2020.

I am trying to develop a recursive code to the above equations.  Note, U,X&Y are multivariate functions (in this case bivariate functions of (x,y)) i.e. U=U(x,y), X=X(x,y) etc.

Dear all

I have a nonlinear system of algebraic equations, I would like to solve it  without using fsolve and Newton's method. 
Maybe one can use, fixed point method or Broyden's method

Fixed_Broyden_method.mw

Can we solve the system of 4 equations, using the proposed methods

thank you 

Hello;

Hope you are fine. Can i apply numerical scheme on maple for the following problem. This in integro-differential equation i think. Waiting for kind response.

Thanks

 

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