Principal component analysis-matlab

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In summary, the conversation is discussing how to find the error of the principal component analysis (PCA). The individual is attempting to find the principal components by subtracting the mean and using the singular value decomposition (SVD) method. They are then asked to find the principal components with 3, 4, and 5 components, and to calculate the mean squared error (MSE) for the results.
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nikki92
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Homework Statement


How do I find the error of the PCA?

||x1hat - x1||^2 + ...+ ||xnhat-xn||^2 so xnhat is the pca one. What is xn?
 
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  • #2
can you elaborate more? having some trouble guessing what your notation means.
 
  • #3
Basically x= randn(100,15)
x_centered=(eye(100)-(1/100)*ones(100,100))*x to subtract the mean to center the data
[s,d,v]=svd(x_centered);

I need to find the principal components
which just the eigenvalues but according to my professor {divi}for i = 1 to 15.
Then I am asked what is the pca with 3, 4, 5 components. For 3 components is it just [d1v1 d2v2 d3v3]

Then I am asked to find the mse of it. I am confused what do I compare the PCA of 3 components to to take the F- norm?
 
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Related to Principal component analysis-matlab

1. What is Principal Component Analysis (PCA)?

PCA is a statistical method used to reduce the dimensionality of a dataset by identifying the underlying patterns and extracting the most important features. It does this by transforming the original variables into a new set of uncorrelated variables called principal components.

2. How is PCA performed in MATLAB?

In MATLAB, PCA can be performed using the pca function in the Statistics and Machine Learning Toolbox. This function takes in a dataset as input and returns the principal components and corresponding eigenvalues.

3. What are the applications of PCA?

PCA is commonly used in data analysis and machine learning tasks, such as data compression, feature extraction, and data visualization. It is also useful for identifying patterns and relationships in high-dimensional datasets.

4. How do you interpret the results of PCA?

The principal components returned by PCA represent the directions of maximum variance in the dataset. The first principal component explains the most variation in the data, followed by the second component, and so on. The eigenvalues associated with each component represent the amount of variance explained by that component.

5. Are there any limitations to using PCA?

While PCA can be a useful tool for dimensionality reduction, it may not always be appropriate for every dataset. One limitation is that it assumes a linear relationship between variables, so it may not capture nonlinear relationships. Additionally, the interpretation of the principal components may not always be straightforward and may require further analysis.

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