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I have a data set of 3 different variables, each variable has 37 data points as follows: 

Variable_1 = [0.489274770173646 0.534659090909091   0.496806966618287   0.593160935871933   0.542091836734694   0.514607775477341   0.580715497052410   0.542977656178750   0.624465240641712   0.644904791797447   0.444644611857190   0.464080100125156   0.522286821705426   0.507719139590466   0.612791008830612   0.561735261401557   0.524166666666667   0.526627218934911   0.449009900990099   0.472768878718535   0.488477561567263   0.576187425642902   0.558307692307692   0.609308792372882   0.647109905020352   0.513392857142857   0.454701120797011   0.557692307692308   0.511568509615385   0.440248676030394   0.500000000000000   0.593340146482712   0.518269230769230   0.623676307886835   0.563086974275214   0.609080188679245   0.769444444444444] 
Variable_2 = [0.573717948717949 0.489656381486676   0.443821689259645   0.578812453392990   0.678328092243187   0.476432291666667   0.460748792270531   0.593650793650794   0.585645494152717   0.540435139573071   0.536423112870416   0.471528337362342   0.514469014469015   0.459801313718039   0.674409015942826   0.526881720430108   0.437327188940092   0.531890398342160   0.479985035540591   0.449145299145299   0.553381642512077   0.524932614555257   0.652630308880308   0.561587521131090   0.560003234675724   0.537254901960784   0.521990521327014   0.466041489059392   0.571461291800275   0.413770728190339   0.493939393939394   0.458024968229051   0.579528535980149   0.512145748987855   0.567205861018424   0.463562753036437   0.562938596491228] 
Variable_3 = [0.630327868852459 0.521367521367521   0.467658730158730   0.485012755102041   0.523217247097844   0.449032738095238   0.574519230769231   0.594594594594595   0.544390243902439   0.581524147097918   0.487662337662338   0.497564726993079   0.417307692307692   0.609668109668110   0.508928571428572   0.511870845204179   0.444067796610169   0.562337662337663   0.494043887147335   0.530476190476191   0.484235294117647   0.502136752136752   0.632418524871355   0.528787878787879   0.619780219780220   0.416958041958042   0.552419354838710   0.586057692307692   0.461351186853317   0.495276653171390   0.524305555555555   0.655671296296296   0.496873496873497   0.462542087542088   0.660491689750693   0.772549019607843   0.558589870903674]

I put all three variables in a matrix, where the columns are the variables and the rows are the 37 data points.

I uses the PCA function in MATLAB and it gives me the following matrix: 

PCA = 0.6370    0.3070    0.7071
      0.3494    0.7026   -0.6199
      0.6871   -0.6420   -0.3403

First Question: What does each row and each column represent in the PCA matrix.

Second Question: How can I use this matrix to plot each variable along its principle component in 3 dimensions.

Thank you, I very appreciate any help

benten
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chinkare_16
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    You need to read about eigenvectors to understand it. PCA==eigenvectors. – Ander Biguri Mar 04 '16 at 16:28
  • Your first question is off-topic here, you should ask that at http://math.stackexchange.com – Adriaan Mar 04 '16 at 16:29
  • You can read an informative post about how PCA works on Cross Validated: http://stats.stackexchange.com/questions/2691/making-sense-of-principal-component-analysis-eigenvectors-eigenvalues. I recommend reading user amoeba's answer instead of the highest voted answer: http://stats.stackexchange.com/a/140579/86678 – rayryeng Mar 04 '16 at 23:00

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