The data file contains three variables: trainx, trainy, testx.

- trainx is a 463715×90 matrix of training data, where each row is a 90-dimensional feature representation of a song.
- trainy is a 463715×1 vector of labels associated with each training data. Each row is the release year of the corresponding song in trainx.
- testx is a 51630×90 matrix of test data.

Special note for those who are not using Matlab: Python users can use scipy to read in the mat file, R users can use R.matlab package to read in the mat file.