How to create parametrized matrix

Question

I would like to create parametrized matrix with given relationship between arguments like this:

B= @(A) [1*A(1), 2*A(2), 3*A(3), 4*A(4)];

But matrix is huge and cannot be created by constant expression like this. I need something like this:

for i=1:N
    B(i) = @(A) i*A(i);
end

Creating matrix this way is not possible and the cell array did not helped me, because this (bellow) is also not valid.

B = @(A) cell(1,N);
for i=vec
    B(i) = @(A) i*A(i);
end

B = @(A) [1:numel(A)].*A?

beaker
– beaker

2023-07-23 14:43:45 +00:00
Commented Jul 23, 2023 at 14:43 — beaker
– beaker, Commented Jul 23, 2023 at 14:43

Thales · Accepted Answer · 2023-07-23 12:21:23Z

0

What about creating a function?

function B = create_matrix(A,n)
    B = zeros(1,n);
    for ii=1:n
        B(ii) = ii*A(i);
    end
end

answered Jul 23, 2023 at 12:21

Thales

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5 Comments

Ales100 Over a year ago

This is what I have now. But if I put B = create_matrix(A,N), then the matrix is probably allocated newly. I want to speed it up with knowledge of constant dimensions and relationships of parameters inside matrix B - so constant dimensions and variable values due to inserted parameter A.

Thales Over a year ago

please, add a minimal reproducible example of what you want. expected input and output and why this answer does not help you and what you have tried to do

Ales100 Over a year ago

In C langugage, allocation of memory would be something like below and then C[i] will contain pointers to members of A and B. If A and B changes, then C changes. const double* C = (double*) calloc(N, sizeof(double));

beaker Over a year ago

@Ales100 That is what B = zeros(1,n); does: it allocates an array of N doubles and initializes it to zeros.

Ales100 Over a year ago

@beaker but it allocates it every function call -> every update. What I have shown allocates memory only once and then are changes solved by links.

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