function HeatExchangerDesign
% 換熱器系列的最優化設計Optimal Design of Heat Exchanger 
%
%   Author: HUANG Huajiang
%   Copyright 2003 UNILAB Research Center, 
%   East China University of Science and Technology, Shanghai, PRC
%   $Revision: 1.0 $  $Date: 2002/04/22 $

x0 = [150  250];        % 給定初值 (here x represents T)
options = [];           % 使用默認參數
xL = [100  100];        % 設定下限
xU = [300  400];        % 設定上限

[x,f,flag] = fmincon(@HeatExchangerArea,x0,[],[],[],[],xL,xU) 
% 結果：T = x = [182.02  295.60], f = 7049.25, flag = 1

% ------------------------------------------------------------------
function f = HeatExchangerArea(T)
T1 = T(1);
T2 = T(2);
f = 1e5*(T1-100)/120/(300-T1)+1e5*(T2-T1)/80/(400-T2)+1e5*(500-T2)/4000;