function temp_k = f2k(temp_f)
% Function f2k converts Fahrenheit temperature to Kelvin.
%
% Converts Fahrenheit temperatures to Kelvin and returns result. Returns
% NaN if temperature is out of range.
%
% Input(s)
%
% temp_f -- The Fahrenheit temperature to be converted.
%
% Output(s)
%
% temp_k -- The Kelvin equivalent returned by the function.
%
% Revsion History
%
% Created 11/27/06 by Dr. C. S. Tritt
%
% Variables Used
%
% temp_f -- Entered temperature in Fahrenheit.
% temp_k -- Converted temperature in Kelvin.

%Convert to Kelvin & check for validity.
    temp_k = 5./9.*(temp_f - 32.) + 273.15;
    if (temp_k < 0.) temp_k = NaN;

end % function f2k.