function [Td] = dp(Ta,rh)

% This MATLAB function computes the dew point tempearture.
% Formula from Wikipedia.
% Claims accuracy of +-0.4 deg C.
% Valid for 0 deg C < Ta < 100 deg C.
%
% Input:  Ta = air temperature in deg C (can be a vector).
%         rh = relative humidity in percent.
% Output:  Td = dew point temperature in dec C (vector if Ta is a vector).
%
% Brian Hornbuckle, November 23, 2006.

% ----------------------------------------------------

% change relative humidity to fraction

rh = rh./100;

% calculate gamma factor

a = 17.27;  b = 237.7;

gamma = a.*Ta./(b + Ta) + log(rh);

% calculate dew point temperature

Td = b.*gamma./(a - gamma);