Error using bsxfun
Requested 900000000x1 (6.7GB) array exceeds
maximum array size preference. Creation of arrays
greater than this limit may take a long time and
cause MATLAB to become unresponsive. See array
size limit or preference panel for more
information.
Error in comparison2 (line 81)
S1 =
fitcknn(array2table(X_norm),y,'NumNeighbors',K3,'Standardize',1

Error using fitcknn (line 247)
FITCKNN does not support tall arrays.