fid = fopen(train_data, 'r', 'b'); in matlab

In Matlab, you can use the fopen function for opening a file. The b flag is not necessary as it is for Windows systems that distinguish between text and binary files, whereas Matlab treats all files as binary by default. Here's the syntax for opening a file in read mode using fopen in Matlab:

main.m
fid = fopen(train_data, 'r');
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Where train_data is the name of the file you want to open in read mode and fid is a file identifier that you can use later to read data from the file using functions such as fread or fgets.