Hi, all, Is there a way to extract all the variables in a list of polynomials? For example: L:=[2*a*b,x^2+y,d*y^2]; I want to get [a,b,x,y,d]. The order of variables does not matter. Thanks Gepo

In our previous article we described a packed representation for sparse polynomials is designed for scalability and high performance. The expand and divide commands in Maple 14 use this representation internally to multiply and divide polynomials with integer coefficients, converting to and from Maple's generic data structure described here. In this post I want to show you how these algorithms work and why they are fast. It's a critical stepping stone for our next topic, which is parallelization.

Hi all,

I am pretty new to maple so forgive me if i am asking a basic question.

I have created a simple loop to evaluate the sum of  1/(k^2)+3, for k from 1 to n, where in this case n = N*20. here is my code and it works ok (for N=1), i have checked with the built in add/evalf functions.

sm := 0: N := 1:  n := N*20

for k from 1 to n do

sm := sm+(1/(k^2)+3):

end do:

evalf(sm);

Given a set of data points, say X={...} and Y={...}, how do I use the Least Squares operation (or another operation if necessary) to fit the curve y=a*x^b to the data points and find the constants a and b. Any help is appreciated. Here is what I have tried:

with(CurveFitting):

LeastSquares([X,Y],v,curve=a*x^b);

And I get an error that the curve is not linear. Help please.

Hi everybody,

I just started using maple for my research few days ago and I would need some help. With "for" loop, I created many matrices and now I would like to create a plot using the first element (A[1,1]) of every matrix. I tried the conventional plot command but without success. It only plot the first and the last value. 

here is an example.

If the first element of the mattrixces is the following C[i][1,1] where i=1..10

I tried to use the following command:

plot(C[x][1,1],x=1..10, style=point)

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

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?

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],