Update README.md

Added minimal REQUIREMENTS, INSTALLATION, and USAGE sections and a reference to the COPYING file containing licensing info.

README.md

@@ -2,6 +2,32 @@
 
 Software to carry out Principal Component Analysis (PCA) of experimental (or simulated) data. 
 
-This software was originally developed by Jorge Quintanilla as part of a collaboration involving Stuart Gibson, Robert Twyman, Gunnar Moller and Tymoteusz Tula, all at the University of Kent.
+This software was originally developed by Jorge Quintanilla as part of a collaboration involving Stuart Gibson, Robert Twyman, Gunnar Moller and Tymoteusz Tula, all at the University of Kent. For licensing information, see COPYING.
 
 This software is optimised for Octave but can be easily adapted for use with Matlab.
+
+REQUIREMENTS
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+A working installation of Octave (the software has been tested on Octave 3.4.3; the source code has comments explaining how it can be adapted for use on Matlab).
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+INSTALLATION
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+No installation required - just place the file functions_PCA_current.m in your working directory.
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+USAGE
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+Start Octave.
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+Type the command 
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+ source "functions_PCA_current.m"
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+This will make available the following Octave functions: 
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+PCA
+gen_A
+gen_image_matrix
+recons
+scores
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+The usage of each of these functions is documented thorugh comments within its source code.