Exercise:PCA in 2D
From Ufldl
(→Step 1b: Check xRot) |
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==== Step 1b: Check xRot ==== | ==== Step 1b: Check xRot ==== | ||
| - | Compute <tt>xRot</tt>, and use the <tt>scatter</tt> function to check that xRot looks as it should, which should be something like the following: | + | Compute <tt>xRot</tt>, and use the <tt>scatter</tt> function to check that <tt>xRot</tt> looks as it should, which should be something like the following: |
[[File:pca_xrot_2d.png|360px]] | [[File:pca_xrot_2d.png|360px]] | ||
| - | Because Matlab/Octave could have returned <math>\textstyle -u_1</math> and/or <math>\textstyle -u_2</math> instead of <math>\textstyle u_1</math> and <math>\textstyle u_2</math>, it's also possible that you might have gotten a figure which is "flipped" or "reflected" along the <math>\textstyle x</math>- and/or <math>\textstyle y</math>-axis; this is also completely correct. | + | Because Matlab/Octave could have returned <math>\textstyle -u_1</math> and/or <math>\textstyle -u_2</math> instead of <math>\textstyle u_1</math> and <math>\textstyle u_2</math>, it's also possible that you might have gotten a figure which is "flipped" or "reflected" along the <math>\textstyle x</math>- and/or <math>\textstyle y</math>-axis; this is also completely correct. |
=== Step 2: Dimension reduce and replot === | === Step 2: Dimension reduce and replot === | ||
