B.4. THE M-H-L METHOD FOR EXAMPLE 3.3 231
% Use the limit state function to determine x0(4)
x0(4)=(4*x0(3)*x0(2)/pi/x0(1))^0.5;
% Store initial design point
for i=1:4
dpp(1,i)=x0(i);
end
% Iterative process
for j=2:1000
% The Tylor series coefficent
G1=sx(1)*1;
G2=sx(2)*(-4)*x0(3)/pi/x0(4)^2;
G3=sx(3)*(-4)*x0(2)/pi/x0(4)^2;
Gd=sd*8*x0(3)*x0(2)/pi/x0(4)^3;
G0=(G1^2+G2^2+G3^2+Gd^2)^0.5;
%Calculate the new design point
x1(1)=mx(1)+sx(1)*beta*(-G1)/G0;
x1(2)=mx(2)+sx(2)*beta*(-G2)/G0;
x1(3)=mx(3)+sx(3)*beta*(-G3)/G0;
% Use the limit state function to determine x1(4)
x1(4)=(4*x1(3)*x1(2)/pi/x1(1))^0.5;
% Update the dimension-dependent Kt
dd=x1(4)-sd*beta*(-Gd)/G0; % New value for
% the dimension
mx(3)=StressAxial( D, dd, r ); % Update Kt
sx(3)=0.05*mx(3);
% Data of iterative process
for i=1:4
dpp(j,i)=x1(i);
end
dpp(j,4+1)=abs(dpp(j,4)-dpp(j-1,4));
% Check the convengence condition
if dpp(j,4+1)<=0.0001;
break
end
% Use new design point to replace previous
% design point
for i=1:4
x0(i)=x1(i);
end