Implementation of a matrix

Hello!

I want to implement the following matrix:

Can anyone show me how to do that?

[KSSV]

Implement how?

[Franziska Bömann]

I have given a vector and from this I want to create the matrix

Answer 1

[Bruno Luong]

n=3;

>> x=ceil(5*rand(1,n+1))

x =

     3     5     1     3

>> M=fliplr(vander(x))

M =

     1     3     9    27
     1     5    25   125
     1     1     1     1
     1     3     9    27

[Franziska Bömann]

I don't know the functions fliplr and vander, is there an easier way to do it?

[Bruno Luong]

Well if I assume using only stricty things you know, I'll end up unable to answer your question.

You kow this?

x(:) .^ (0:length(x)-1)

or this?

M = zeros(length(x));
for k=0:length(x)-1
    for i=1:length(x)
        M(i,k+1) = x(i)^k;
    end
end

or this?

y=x(:);
u=ones(size(y));
M = [u y.*[u y.*[u y]]]

or this?

u = ones(size(x(:)));
M = u(:,[]);
for j=1:length(x)
    M = [u, x(:).*M];
end

[Franziska Bömann]

thank you, that's what I was looking for.

[madhan ravi]

It’s wrong. Should be without -1

[Bruno Luong]

Think more carefully madhan, n is length(x)-1 (you store where x_0?)

[Franziska Bömann]

That's right Bruno!

And another question:

I created y=1+sin(x(:)).^2 but the output is wrong, why?

[Bruno Luong]

What's the relationship between y=1+sin(x(:)).^2 and the codes I showed you?

[Franziska Bömann]

I have to solve inv(matrix)*y at the end

[Bruno Luong]

How can you expect me to guess what is wrong without knowing x, or what is solution you expect ? and is the solution you get with MATLAB? or what exact MATLAB code you try?

I need a crystal ball.

[Franziska Bömann]

x is a random vector with n indices, I get the first solution at f and the others are all 0, which is wrong

[Franziska Bömann]

I got it now!

[Bruno Luong]

Then your code is likely wrong. You want me to point out where it's wrong? Let me look at my christal-ball: it tells me line #4, column #7 of your MATLAB script

Answer 2

[madhan ravi]

 x(:).^(0:numel(x))

[Franziska Bömann]

thank you!

Answer 3

[KSSV]

syms x [ 4 4]