%最速下降梯度法matlab程序
% Steepest Descent Method
% By Kshitij Deshpande
clc
clear all
warning off
prompt = {\'Coeficients ifX1=\',\'Coefficients of X2=\',\'Coefficeint of X1X2=\',\'Initial Point=\'};
def
= {\'[2 1 0]\',\'[1 -1 0]\',\'2\',\'[0 0]\'};
a=inputdlg(prompt,\'Data\',1,def);
a=char(a);
[m,n]=size(a);
x1 =eval(a(1,1:n));x2=eval(a(2,1:n));x1x2=eval(a(3,1:n));X1=eval(a(4,1:n));
delf1(1) = polyval(polyder(x1),X1(1));
delf1(1) = (delf1(1))+(x1x2*X1(2));
delf1(2) = polyval(polyder(x2),X1(1));
delf1(2) = (delf1(2))+(x1x2*X1(1));
s=-delf1;
%%%%%%%%%%
%report
srep(1,1:2)=s;
%%%%%%%%%%

x1new(1)=s(1)^2;x1new(2)=2*X1(1)*s(1);x1new(3) = X1(1)^2;

x1new=x1new*x1(1);

x1new_(2)=x1(2)*s(1);x1new_(3)=x1(2)*X1(1);

x1new = x1new+x1new_;



x2new(1)=s(2)^2;x2new(2)=2*X1(2)*s(2);x2new(3) = X1(2)^2;

x2new=x2new*x2(1);

x2new_(2)=x2(2)*s(2);x2new_(3)=x2(2)*X1(2);

x2new = x2new+x2new_;

x1x2new(1)=s(1)*s(2);x1x2new(2)=X1(1)*s(2)+X1(2)*s(1);x1x2new(3)=X1(1)*X1(2);

x1x2new=x1x2*x1x2new;

df =polyder(x1new+x2new+x1x2new);

lambda(1) = roots(df);