CODEWITHSUNDEEP
matrixmaxima
Hirshy
Hirshy

Reputation: 157

Maxima: define columns of matrix as a vector

In Maxima I want to define vectors using the columns of randomly generated matrix where not only the entries but also the number of rows and columns is random. My code so far:

n:2+random(5);
m:2+random(5);
h[i,j]:=5-random(11);    
M:genmatrix(h,n,m);

The number of rows/colums can ranges from 2 to 6 (not neccesarily n=m) and the entries are random integers from -5 to 5.

I can now use

v1:col(M,1);

to define the vector v1 as the first column of the matrix M, but since I don't know how many columns there are I tried this:

for i thru n do (vi:col(Mt,i));

This returns "Done" but when I enter

v1;

I just get "v1" as the result and not the first column of the matrix. With

for i thru n do (disp (v[i]=col(Mt,i)));

I can get Maxima to display all the columns as vectors but again I get just "v1" as the result. Can anyone tell me what I am doing wrong?

Upvotes: 0

Views: 1140

Answers (1)

Robert Dodier
Robert Dodier

Reputation: 17576

I can't test this code right now but I believe this or something pretty similar should work.

Here is a way to generate a random matrix and then extract the columns of the matrix. I don't know if you want to present the columns as column vectors or as row vectors. Maxima doesn't really have a way to represent row and column vectors as distinct types. Instead for a column vector, I'll obtain a matrix of 1 column, and for a row vector, I'll obtain a list.

[m, n]: [2 + random(5), 2 + random(5)];
h: lambda ([i, j], random(11) - 5) $
M: genmatrix (h, m, n);

Here is a list comprising the columns of M as 1-column matrices:

makelist (col (M, k), k, 1, n);

Here is a list comprising the columns of M as lists:

args (transpose (M));

Upvotes: 2

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