steadytemp.m

nonlinear eq routines in matlab

function varargout = steadytemp(T)
%
% compute the function value and derivative of 
%   pi*D*h*(T-Tinf)+pi*D*epsilon*sigma*(T^4-Ts^4)-IR
%
% Temperature T is measured in Kelvin!!
%
%  [y]    = steadytemp(T)
%  [y,yp] = steadytemp(T)  returns the function value in y and 
%                          the derivative in yp
%
%  Matthias Heinkenschloss
%  Department of Computational and Applied Mathematics
%  Rice University
%  March 29, 2001
%

sigma   = 5.67e-8; % Stefan Boltzman constant
epsilon = 0.8;
h       = 20;
Tinf    = 25+273.15;  % Temperature in K
Ts      = 25+273.15;  % Temperature in K
D       = 0.1;
IR      = 100;

% return the function value
varargout{1} = pi*D*h*(T-Tinf)+pi*D*epsilon*sigma*(T^4-Ts^4)-IR;
if( nargout > 1 )
  % return the derivative as the second argument
  varargout{2} = pi*D*h+4*pi*D*epsilon*sigma*T^3;
end