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Hi, I'm working on the Smoluchowski equation (essentially the diffusion eqn with an extra derivative) diff(u(x,t),t)=k*diff(u(x,t),x)+D*diff(u(x,t),x,x) k is piecewise so the function has to be solved numerically, the boundary values are specified u(0,t)=u(1,t)=0 but i need the derivative at the boundaries D[1](0,t) and D[1](1,t). It seems to be simple to evaluate a numeric derivative of an ODE but I can't see how to do it for a PDE. Any help welcome, even some sort of brute force method if necessary. Thanks, Ryan

IF statements...

February 24 2010 Jimmy19001 128

I understand how to use an IF statement, but what does ' if ' mean??

I have solved a partial differential equation numerically using PDSolve and now I would like to visualise what is happening in my system. I have tried to watch some tutorials on how to do so, but these only explain how to do it when you have a function, rather than a set of numerical results. Also, the animate function of pdsolve only gives me a 2-D plot, however, I would like a 3-D animation. Could anyone give me any tips on how to do so

 

Thanks in advance.

Can anyone please write a procedure to multiply 2 matrices in maple ??
(  it has to be a written procedure so without using maple built in multiplication matrices function )
thankssss

Hi, all, Is there a way to compare two lists containing polynomials to check whether they are equal? Thanks Gepo

hello all,

i attach the worksheet. It shows an 'invalid object' error. i really cant figure out what is wrong. can someone have a look please?also, is there any way to get maple to point me to where it finds errors?

View 16354_take1.mw on MapleNet or Download 16354_take1.mw
View file details

 

Lovinash

Dear All,

I wonder if anyone could perhaps offer some advice concerning evaluation of the following definite integral in closed form.  The integral is defined in the principal value sense and arises in a problem involving integration over an ellipse with the axes given by a and b. The command int(...) (see below) used in Maple 13 does not seem to deliver any result in finite time. Thanks a lot!  Bartek
 

I am using NLPSolve to maximize the the sum of pij*LN(pij) over i and j subject to linear boundary conditions. I notice the help page for NLPSolve says it finds a global max if the objective function is convex. I expect Maple can figure out if x*LN(x) is convex, but I had to define f(x)= xLN(x) if x<>0 and f(0)=0. Does Maple determine whether this function is convex? How? Is there a place for me to declare it convex? Or does the algorithm just al;ways work ( to find a global max) if the objective is convex?

I'm graphing the quadratic form of a 2x2 matrix in maple TA. I've got the graph to display, but now I'm trying to add other things to it. So far I've been unable to figure out how to add a label or gridlines to the graph in Maple TA (adding gridlines in Maple is easy enough, but these don't show up in TA). Here's my code so far;

$eigvs=maple("with(LinearAlgebra):
E,V:=Eigenvectors(<<7,6>|<6,12>>);
newcoords:=V.<x,y>;
[E,V,newcoords]");

My coursemate and I tried to solve a differential equation using the following code:

>PDE := diff(Sigma(R, t), t) = 3*(diff(R^.5*(diff(Sigma(R, t)*R^.5, R)), R))/R;
>IBC := {Sigma(0, t) = 10, Sigma(R, 0) = 0};
>pds := pdsolve(PDE, IBC, numeric, Sigma(t, R), indepvars() = (R, t), time = t, range = 0 .. infinity)
%
Error, (in pdsolve/numeric/par_hyp) Incorrect number of boundary conditions, expected 2, got 1

Hello

I need a procedure, or command, which will identify the unique sets which sum to 1 (from a permuted list).

by way of explanation:

> with(combinat);

>A := permute([1, 1, 0, 0, 0, 0, 0, 0], 8);


[[1, 1, 0, 0, 0, 0, 0, 0], [1, 0, 1, 0, 0, 0, 0, 0], [1, 0, 0, 1, 0, 0, 0, 0],

  [1, 0, 0, 0, 1, 0, 0, 0], [1, 0, 0, 0, 0, 1, 0, 0],

  [1, 0, 0, 0, 0, 0, 1, 0], [1, 0, 0, 0, 0, 0, 0, 1],

  [0, 1, 1, 0, 0, 0, 0, 0], [0, 1, 0, 1, 0, 0, 0, 0],

Hi,

I want to make a 3D plot of the following function of alpha and beta:

Hi, Solving a non linear eq. system I got the solution posted below. Here I only show one solution for a certain value of "a2", but in fact I got n rigs as n values of "a2" I am interested.

The Question is:How can I isolate a value from this solution,for instance to create a vector with the several "P" results for each solution given.Thanks,JPA

With a Mac using Firefox you would hold command + alt and left or right arrows to change between tabs.

 

How would you do this in Maple? Does such a feature exist?

Hello all,

I'm running into a bit of a problem finding an efficient way of forming the expansion coefficient for an eigenfunction expansion. The way I currently have it coded works, and it doesn't take terribly long (about 30 seconds or so). However, I have to run a lot of different evaluations, so all that time begins to add up. In addition, the memory usage balloons until I am pretty much frozen and unable to complete the calculations.

So, here's the block of code that's causing me problems:

for p to P do

for q to Q do

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