CODEWITHSUNDEEP
algorithmmatlabiteration
user466534
user466534

Reputation:

Iterated algorithm for creating data matrix

suppose that i want to create following data matrix

enter image description here

for creating such type of matrix, i have already written code

function [ x ]=create_matrix1(b,l)
    n = length(b);
    m = n-l+1;
    x = zeros(m,l);
    for i=1:m
        x(i,:)=b(i:i+l-1);
    end;
end

but when we have a large data, then creating of such matrix became big problem, for instance if we generate data from matlab like this

load ampoutput2.mat
[m n]=size(y)

m =

      500000


n =

     1

if p=2000 then of course it will crush, computer will stop working, is there any iterated version which i can do for creating this matrix?thanks very much

Upvotes: 0

Views: 77

Answers (2)

rahnema1
rahnema1

Reputation: 15867

the matrix can be efficiently created this way:

create_matrix2 = @(b, l) b(bsxfun(@plus, (1 : l), (0 : numel(b)-l)'));

Upvotes: 1

CKT
CKT

Reputation: 781

I think what you want is the hankel function. But you may not want to explicitly construct the matrix, depending on what you want to do with it. You can multiply matrices of this type against vectors in O(N log N) time with some calls to flip and by using the FFT.

Upvotes: 1

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