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

Hi, all, I have a list of polynomials and then I want to get polynomials which include given variables. How can I do this? For example, I have a list: L:=[a+b+c,x+ab+d^3,y+c]; and I am only interested in polynomials which include varaibles "a", "b", "c", which is "a+b+c". Which command can implement this? thanks Gepo

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

How do i convert a curve into its data points i.e. how can  i get the points from a curve.

Thanks

Hello,

I have a system of polynomials that I need to calculate its primedecomposition.

It has been trying for several hours but it could not give me result.

Even I tried to have Grobner basis and I could not.

Could you please let me know what should I do for that?

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I dont understand what's the 'label' thing in the answer here.

 

Thanks.

 

casper

Suppose I want a random sample of 500 numbers

RandomSample(Normal(0,1)),500);

Good, now if I am understanding properly [0,1) means positive values with a mean of 0 and standard deviation of 1.  However in Maple RandomSample(Normal[0,1)),500); is not allowed due to bracket mismatching. 

how do I get the RandomSample domain [0,1)?

Hi all I've a program running that has been stopped with the error Execution stopped: Stack limit reached. at that time the program was using memory used=480073.6MB, alloc=594.8MB, time=16330.02 The host computer has 16 CPUs and 50Gb of Ram, so I don't think the problem is the memory... Any hints? Thanks Salvo ps: I've found an old discussion about this problem, but it was very old (2005, M9) so I've thought I could open a this one.

I am trying to solve a set of 4 coupled ordinary differential equations, starting from certain set of initial conditions for certain parameter values.  i have to evolve the system for a very long time (higher number of iterates are needed).

For a certain set of initial conditions the following error occurs

"Error, (in sol12) cannot evaluate the solution further right of 2939.9221, probably a singularity"

what could be the possible way to get rid of this error.......

I'm new to programming.

I don't understand what I'm doing wrong in this