function max( arr, j, len ) {
	var max;
	var x;
	var i;

	max = arr.get( 0, j );
	for ( i = 1; i < len; i++ ) {
		x = arr.get( i, j );
		if ( x > max ) {
			max = x;
		}
	}
	return max;
}
Returns the maximum value.

@private
@param {ndarrayLike} arr - input array
@param {number} j - column index for which to get the maximum
@param {number} len - number of rows in arr
@returns {number} maximum value