Assigning values to a matrix in a particular way for an algorithm

Question

Amanpreet Singh 2015-3-15

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评论： Amanpreet Singh 2015-3-16

Hi I need to construct a (n,m) matrix like :

            x(0)   x(-1)  x(-2)..........
            x(1)   x(0)   x(-1)..........
            x(2)   x(1)   x(0)...........
            .............................
            .............................
            x(n-1) x(n-2)          x(n-m)

x(n)is an input signal- x(0),x(1),x(2)....x(n-1) which will be generated by rand command.

I need this matrix for an algorithm.

Can anyone show me how to assign these input values in this matrix form?

And what about x(-1), x(-2) etc in the very first stage? Should they be kept zero?

Thank you

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Answer 1

Guillaume 2015-3-15

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https://ww2.mathworks.cn/matlabcentral/answers/183276-assigning-values-to-a-matrix-in-a-particular-way-for-an-algorithm#answer_171437

在 MATLAB Online 中打开

Your matrix is a toeplitz matrix which you can generate with the toeplitz command.

As to your question "And what about x(-1), x(-2) etc in the very first stage? Should they be kept zero?". How should we know? It's your algorithm, hence your decision to make. Assuming you want 0:

x = rand(1, 5)
m = toeplitz(x, [x(1) zeros(1, numel(x)-1)])
%note that if you don't mind the warning message
%m = toeplitz(x, zeros(size(x)))
%works just the same