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Khan Academy: Linear Algebra
Not really a stand alone linear algebra class (more as a supplement), but contains lots of good information.
Open Courseware: Linear Algebra
Open Courseware: Matrix Methods i n Data Analysis, Signal Processing, and Machine Learning
The follow-on course to the introduction linear algebra class. Matrix methods expands on the fundamental concepts discussed and introduces some additional ideas that are also very useful, such as positive-definite matrices, singular value decomposition, etc.
edx.org: Linear Algebra Courses
Free (or paid, if you want a certificate), self-paced linear algebra courses from a number of institutions.
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Zach Star
StatQuest with Josh Starmer (Genetics Dept., University of North Carolina at Chapel Hill)
Nice explanations of (among other things):
Scaling: so as not to artificially weight data measured at different scales.
Centering: SVD expects data at the origin, so PCA expects data to be centered at the origin.
STHDA
Data4Bio
Julia Silge
Code Emporium
Principal Component Analysis (PCA) - The Math You Should Know!
A deep dive into the mathematical justification of PCA.
Luis Serrano
Principal Component Analysis (PCA)
One of the best explanations of PCA I’ve seen.