## MATRIX CHANGING VALUES WHEN RUN TWICE...

Hi,

I have this program which when I run gives me five unique matrices as I want it. I however, when I run it again the enries of the matrices changes and I get 5 identical matrices, how can I prevent this from happening?

Vic

## Find indices of unique elements in a list...

Hi there,

I've been trying to find an equivalent to MATLAB's unique command in Maple, but I had no success.

I've seen that Maple would return the elements that are either repeated (FindRepetitions) or not repeated (MakeUnique), but not the indices within the original list.

Is there way to do that?

Thanks,

jon

## Large system of Equations Mod 2...

Hi i 2 questions. all pertaining to solving a systems of equations mod 2

First if i have a large set of equations, 11^3 equations in 11 unknowns and i want maple to give me ALL solutions mod 2 how can i do that? Maples msolve is loosing solutions.

Second suppose i want all unique solutions that say 6 of the variables can have but dont care what the solution to the other variables are as long as it is a solution.

mini example:

say x=1,y=1,z=1 is a solution as well as x=1,y=1,z=0, i just want to know about x=1,y=1.

## is there a member() function for Vectors ?...

Hi there,

I have a piece of code that uses lists instead of vectors and recently, it crashed, it ran out of memory. Long story short, if I use vectors instead of lists, the performance is much better and optimal (this I knew but I was lazy to translate all my code). However, there's one single line that I cannot efficiently translate and it's the one that uses the function member(). Before, I had the following (it's an oversimplification of my code in order to easily discuss it in here):

## ListTools count for each unique element...

I frequently have a list of numbers and what I want is a sorted list of unique elements with a count of how many times each element appears.  Is there some way to do this with ListTools?

Here is my code:

listhist := proc(L)
local S, T, i;
T := table(sparse):
for i in L do T[i] := T[i]+1; end do;
S := sort(map(op,[indices(T)]));
[seq([i,T[i]], i=S)];
end proc:

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