how to solve system of linear equations to fit the set of constraints i have

I have a program that need to check for each set of values- bound limits and coupled constraints. But every time i try to run it it may go beyond the limits or the constraints are not satisfied. What modification i can do. The code goes like this:-

function [ gout ] = c(gac,cy)
gout=gac;

%% Uncoupled Constraints 
lbac=[220 260 50 25];                     
ubac=[260 1000 400 600];                      
U=(gac>ubac);
gout(U)=ubac(U);
gout(~U)=gac(~U);
L=(gac<lbac);
gout(L)=lbac(L);
%% Coupled constraints
if gout(2)-gout(3)-gout(4)-20<0 
 [~,I]=max(abs([ gout(3) gout(4) gout(2)]-[ lbac(3) lbac(4) ubac(2)]));
  switch I
      case 1
          gout(3)=gout(2)-gout(4)-20; 
          if (gout(3)>ubac(3) || gout(3)<lbac(3))
            gout(3)=min((gout(2)-gout(4)-20),lbac(3));
          end 

        case 2
            gout(4)=gout(2)-gout(3)-20; %modification related to hc
            if (gout(4)>ubac(4) || gout(3)<lbac(3))
             gout(4)=min((gout(2)-gout(3)-20),lbac(4));
            end 

        case 3 
            gout(2)= gout(2)+(gout(3)+gout(4)-gout(2)); 
             if gout(2)-gout(3)-gout(4)-20<0
                gout(2)=min((gout(3)+gout(4)),ubac(2));
            end 
    end 
end 
gout = ceil(gout);
end

I am getting a gac vector and want to fit in with all the constraints and pass the modified value to other function.