solve returns empty set

Hello there is this weird thing going on where solve command gives me empty set to everything I put when I run my program ----

% EE 589 project
%Range estimation
%Ri=[(x-xi)^2+(y-yi)^2)^1/2
%ri=ri-r1
%s=x^2+y^2
%ki=xi^2+yi^2
%d=cti=ru+ei

    c=3*10^8 ; %speed of light

    T0= input('Enter your TOA vector '); 
    n=size(T0,1);
    sigma=-1;
    while( sigma <0)
      sigma= input('Enter variance of noise ');
  end

      e=sigma*randn(n,1); %%defining noise
  T=T0+e; %%Adding noise to data
  Q=var(e)*eye(n); %%Defining covariance matrix
  xi=input('Enter x coordinates of sensors');
  yi=input('Enter y coordinates of sensors');
  while(size(xi,1) ~=n | size(yi,1) ~=n)
      xi=input('Enter x coordinates of sensors');
  yi=input('Enter y coordinates of sensors');
  end
  M=transpose([xi yi]);

    d=c*T;

    syms S;

    k=xi.^2+yi.^2;
    b=S*ones(n,1)+k-d.^2;

    LS=inv(M*transpose(M))*M*b;
    [x,y]=deal(LS(1),LS(2));
    syms Initialvalue;
    Initialvalue = solve(S==x^2+y^2);
    initialvalue=double(Initialvalue); 
    roots=initialvalue;

    case1=0; if (roots(1)<0  && (roots(2)>0&&imag(roots(2))==0))
       s=roots(2);
       case1=1;
   end

   if (roots(2)<0  && (roots(1)>0&&imag(roots(1))==0))
       s=roots(1)
       case1=1;
   end

   case2=0;
    if (case1~=1)
        if((imag(roots(1))~=0))
            s=abs(real(roots(1)));
            case2=1;
        end
        if(case2~=1)
        %case3 both negative comparing for minimum J
        stest1=abs(real(roots(1)));
        stest2=abs(real(roots(2)));

        [xtest1,ytest1]=deal(subs(LS(1),stest1),subs(LS(2),stest1));
        [xtest1,ytest1]=deal(double(xtest1),double(ytest1));
        rtest1=((ones(n,1)*xtest1-xi).^2+(ones(n,1)*ytest1-yi).^2).^.5;
        Jtest1=transpose(T-rtest1/c)*inv(Q)*(T-rtest1/c);

        [xtest2,ytest2]=deal(subs(LS(1),stest2),subs(LS(2),stest2));
        [xtest2,ytest2]=deal(double(xtest2),double(ytest2));
        rtest2=((ones(n,1)*xtest2-xi).^2+(ones(n,1)*ytest2-yi).^2).^.5;
        Jtest2=transpose(T-rtest2/c)*inv(Q)*(T-rtest2/c);
        if(Jtest1<=Jtest2)
            s=stest1;
        end
        if(Jtest1>=Jtest2)
            s=stest2;
        end 
        end 
    end

    [x,y]=deal(subs(LS(1),s),subs(LS(2),s));%assigning LS output to x,y

    [x,y]=deal(double(x),double(y));
    ri=((ones(n,1)*x-xi).^2+(ones(n,1)*y-yi).^2).^.5;%distance from x to sensors 

    for(h =1:5000)
    for( i= 1:n)
      g(i,1)=(x-xi(i))/(ri(i)*(ri(i)+d(i)));
      h(i,1)=(y-yi(i))/(ri(i)*(ri(i)+d(i)));
  end
    A(1,1)=2*sum(g.*xi);
    A(1,2)=2*sum(g.*yi);
    A(2,1)=2*sum(h.*xi);
    A(2,2)=2*sum(h.*yi);
  B(1,1)=sum(g.*(ones*s+k-d));
  B(2,1)=sum(h.*(ones*s+k-d));

    solve=inv(A)*B;
    [x,y]=deal(solve(1),solve(2));

    end

---- if I run this it works and I get the result I want but if i try to run it again it won't work, and the solve command stops working and gives empty set even if i try to solve for like syms s solve(s==1) it will be empty set but only if i run my program

[hamad alduaij]

never mind I figured it out the problem was this somehow

solve=inv(A)*B;
[x,y]=deal(solve(1),solve(2));

I changed solve to solution and it worked out

[Walter Roberson]

You should avoid using inv(A) .

solution = A\B;