%%%three_variable_book.m%%%
clear;clc
w1(1)=8;w2(1)=10;w3(1)=5;eta=0.1;
E=inline('3*(xx-2)^2+2*(yy-3)^2+4*(zz-1)^2+3','xx','yy','zz');
dEdw1=inline('6*(xx-2)','xx');
dEdw2=inline('4*(yy-3)','yy');
dEdw3=inline('8*(zz-1)','zz');
fprintf('(w1(1),w2(1),w3(1)) = (%f,%f,%f),E(w1(1),w2(1),w3(1))=%f \n'...
, w1(1),w2(1),w3(1),E(w1(1),w2(1),w3(1)));
i=1;
tol=1.0e-6;
cost1 = E(w1(1),w2(1),w3(1));
err=2.0*tol;
%%for 문
% for i=1:10
% w1(i+1)=w1(i)-eta*dEdw1(w1(i));
% w2(i+1)=w2(i)-eta*dEdw2(w2(i));
% w3(i+1)=w3(i)-eta*dEdw3(w3(i));
% fprintf('(w1(%d),w2(%d),w3(%d))=(%f,%f,%f),E(w1(%d),w2(%d),w3(%d))=%f \n',...
% i+1,i+1,i+1,w1(i+1),w2(i+1),w3(i+1),i+1,i+1,i+1,E(w1(i+1),w2(i+1),w3(i+1)));
% end
while err>tol
w1(i+1)=w1(i)-eta*dEdw1(w1(i));
w2(i+1)=w2(i)-eta*dEdw2(w2(i));
w3(i+1)=w3(i)-eta*dEdw3(w3(i));
fprintf('(w1(%d),w2(%d),w3(%d))=(%f,%f,%f),E(w1(%d),w2(%d),w3(%d))=%f \n',...
i+1,i+1,i+1,w1(i+1),w2(i+1),w3(i+1),i+1,i+1,i+1,E(w1(i+1),w2(i+1),w3(i+1)));
cost2=E(w1(i+1),w2(i+1),w3(i+1));
err=abs(cost2-cost1);
cost1=cost2;
i=i+1;
end