## Basic Sin wave RP in matlab

General discussions and questions about recurrence plot and recurrence network related methods.
Junior
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### Basic Sin wave RP in matlab

Hello Guys,
I am very much new to RP, I read something about RP in this site. Now my doubt is following.

I have seen, A sin wave generates RP only diagonal lines. The code I have written in matlab generating cross diagonal lines. Once you check it. And please tell me where I am doing mistake?

Code: Select all

``````x=sin(2*pi*linspace(1,11,2000));

t=1:size(x);

N = length(x);
S = zeros(N, N);

for i = 1:N,
S(:,i) = abs( repmat( x(i), N, 1 ) - x(:) );
end

%  imagesc(t, t, S)
%  axis square
thr=0.05;
imagesc(t, t, flipud(S) < thr)
axis square
colormap([1 1 1;0 0 0])
xlabel('Time'), ylabel('Time')``````
the above program is for thershold value (thr) = 0.05;

How to get the exact RP of sine wave?
sultornsanee
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Location: Network/Nano Science and Engineering Laboratory, Northeastern University, Boston, USA

### Re: Basic Sin wave RP in matlab

I recommend to use CRP toolbox. So you can get a right RP and RQA.
Norbert
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Joined: Wed Jan 4, 2006 11:03
Affiliation (Univ., Inst., Dept.): Potsdam Institute for Climate Impact Research, Germany
Location: Potsdam, Germany
Location: Potsdam Institute for Climate Impact Research, Germany

### Re: Basic Sin wave RP in matlab

The answer is that you have not embedded your time series. Without embedding you will similar dynamics in positive and negative time direction, i.e., x(i, i+1, i+2,...) = x(j, j-1, j-2, ...). This will cause diagonals perpendicular to the main diagonal. This should be explained in the Physics Reports paper as far as I remember.