readMNIST(folder)
trainData
and trainLabels
and for the test
data testData
and testLabels
. To start the
function The files "train-images-idx3-ubyte",
"train-labels-idx1-ubyte', "t10k-images-idx3-ubyte", and
"t10k-labels-idx1-ubyte" have to be in the folder given by
the parameter folder
. The folder name must end with
a slash.