The forecast factors are the amount of viruliferous L. striatellus, wind
speed, relative humidity, and insolation duration two pentads before,
three meteorological factors, and one biological factor, four predictors
in total. Predictand is the rate of RSV diseased plants in the current
pentad. It is known that the input node M = 4, output node N = 1,
and the hidden layer node R depends on the empirical formula