function [MM] = dewpointfunction (M)

year = M (:,1);
month = M (:,2);
day = M (:,3);
hour = M (:,4);

T = M (:,5);
RH = M (:,6);

a = 17.271;
b = 237.7;

at = a * T;
bt = b + T;

r = at./bt;

gama = r + log (RH/100);

gama1 = b*gama;
gama2 = a - gama;

dp = gama1./gama2;

MM = [year, month, day, hour, dp];

end