[GitHub] incubator-spark pull request: Principal Component Analysis

[sscdotopen]

Github user sscdotopen commented on the pull request:

    https://github.com/apache/incubator-spark/pull/564#issuecomment-34583075
  
    Centering a sparse matrix like it is done in textbook PCA is a serious 
scalability bottleneck as it densifies the input matrix, not sure if you can 
apply the algorithm like this.