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Posts: 1Member
Hello all!
I am Brian, an electrical engineering student at Vanderbilt University. I am doing some research involving a PCA (Principal Component Analysis) in a spectroscopy project. Most of this code is taken from a tutorial, and I am trying to make it work for my project, where I have only one measurement per time sample instead of several. So, I have a (MxN) (1x2000) matrix, where the 2000 is the number of samples taken sequentially. I am getting an error on line 8. Please tell me why!

function [signals,PC,V] = PCA_analysis_fromTutorial(data)
% PCA1: Perform PCA using covariance.
% data - MxN matrix of input data
% (M dimensions, N trials)
% signals - MxN matrix of projected data
% PC - each column is a PC
% V - Mx1 matrix of variances
MATRIX = importdata('C:UsersBrian NeavesDesktopPETN data for PCA analysis');
N = size(MATRIX);

% subtract off the mean for each dimension
mn = mean(data,2);
data = data - repmat(mn,1,N);
% calculate the covariance matrix
covariance = 1 / (N-1) * data * data;
% find the eigenvectors and eigenvalues
[PC, V] = eig(covariance);
% extract diagonal of matrix as vector
V = diag(V);
% sort the variances in decreasing order
[~, rindices] = sort(-1*V);
V = V(rindices);
PC = PC(:,rindices);
% project the original data set
signals = PC * data;