## Sheet for percolation...

has someone a sheet about percolation theory ? I put a very simple one on my blog: percolation

## First order difference equation !...

Can maple do this ? and how .... I know you can do the graph, but I need to know if maple can do my problem. ex: Y(t+1) + Y(t) = (-1)^t and y(0) = 2

## assuming and procedure parameters...

Hello,

I am looking for an explanation for the following behavior :

> f := proc(x) somefunc(x) end proc:
> a := table([variable=z]):
> f(a);
somefunc(a)
> f(a) assuming z::real;
somefunc(table([variable=z]))

Why is 'a' replaced with its corresponding table in the second case? And is it possible to use the name 'a' in the return value?

-- Thanks for any reply,

Franky.

## Numerical integration...

Hello!

I´m Trying to do numerical integration for a function defined by a product of characteristic functions. I either receive the message " Error, (in unknown) too many levels of recursion " or "error, (in evalf/int) unable to handle singularity". What should I do?

f_1:=(x,y,z,w)->piecewise(x+w > 0 , 1);
f_2:=(x,y,z,w)->piecewise(x*w - y*z > 0,1);
f_3:=(x,y,z,w)->piecewise((x+w)^2 - 4*(x*w - y*z)<0,1);
prod:=(x,y,z,w)->f_1(x,y,z,w)*f_2(x,y,z,w)*f_3(x,y,z,w);

I want to integrate prod, with all four variables ranging from -1 to 1.

Thank you, Bernardo

## Maximam number of variables...

Hi, I am trying to call a Matlab function from Maple. The Matlab function requires 33 input variables, but when I call this function with this many variables I get the following error message: "Error, (in ExecuteCommand) Matlab command string is too long" My objective is to maximize this function using GlobalSOlve but first I want to just call it. I would appreciate if someone can help me with this. Cheers Saqib

## Generating Plots and Legends...

Hi! I have a two part question: I am plotting a matrix as multiple graphs: column1 v column2, column1 v column3 etc I have a worksheet set up so that some of the graphs can be completely equal to 0. I am plotting all the graphs on the one set of axes for comparison, and so the null graphs don't appear. However, I am having problems getting a legend. I only want to display a coloured legend (each plot is a different colour) for each graph that is non zero. How can I do this? Second part, I have created a text box next to the graph that displays the names of the non zero graphs as strings. Can I make these strings the same colour as their respective graphs?

## Locking Subsections...

Hi everyone! I would like to create a worksheet witb multiple worksheets, and I would like to use sections and subsections. Can anyone please tell me how to lock certain sections/subsections closed so users cannot open then? Thanks :)

## How to create this list?...

Hi dear members of this Forum,

I want to generate a list which depend on "n";
for n=2 I would like to generate the following list

>[[p1>q1, p2>q2],
>[p1>q1, p2<q2],
>[p1<q1, p2>q2],
>[p1<q1, p2<q2]]

for n = 3 I would like to generate the list:

>[ [p1+p2>q1, p1+p3>q2, p2+p3>q3],
[p1+p2>q1, p1+p3>q2, p2+p3<q3],
[p1+p2>q1, p1+p3<q2, p2+p3>q3],
[p1+p2>q1, p1+p3<q2, p2+p3<q3],
[p1+p2<q1, p1+p3>q2, p2+p3>q3],
[p1+p2<q1, p1+p3>q2, p2+p3<q3],
[p1+p2<q1, p1+p3<q2, p2+p3>q3],
[p1+p2<q1, p1+p3<q2, p2+p3<q3]]

for n=4

[ [p1+p2+p3>q1, p1+p2+p4>q2, p1+p3+p4>q3, p2+p3+p4>q4],..

## automatic generation of package documentation...

is it possible to implement a package so that the documentation and the help files will be automatically extracted from the sources?

## Lagrange multiplier maximum

by: Maple
As a newbie to maple, I was wondering how do I find the maximum of a equation under contraint. i can find some but for this one I can't ... and it's getting to me f=1000*x+7500*y under constraint: g=10000000-(20000*x^0.8)*y^1.2 and for f=(20000*x^0.8)*y^1.2 under constraint: g=125000-1000*x-7500*y Who do I find the maximum using MAple 10 !!!????

## Unassigning certain user variables...

We have an automated grading system and sometimes students assign values to variables that are useful in grading their assignments. In order to get around this I've been tinkering with the anames() command (specifically, anames(user)), but I cannot seem to get a usable list of "in use" variable names: Every time I try to get Maple to use the list that anames(user) returns, I get the evaluated variable and not the variable name. Example: >a:=4; >anames(user)[1]; 4 Does anyone know how I can get a usable list of variable names that have been assigned values?

## 3D polar contour surfaces with colour superimposit...

Hi, I would like to be able to plot a 3d surface of one variable, with another variable in colour on that surface. This plot should have a legend for the colour variable. At a stretch, I would also like to have all of this in polar co-ordinates, with polar axes and without having to write a transform myself. Is all this possible! cheers