YBUS by Singular Transformation

clc;
clear;
ydata=[1 1 2 1/(0.05+j*0.15) 0 0;
       2 1 3 1/(0.10+j*0.30) 0 0;
       3 2 3 1/(0.15+j*0.45) 0 0;
       4 2 4 1/(0.10+j*0.30) 0 0;
       5 3 4 1/(0.05+j*0.15) 0 0];
elements=max(ydata(:,1));
yprimitive=zeros(elements,elements);
for i=1:elements;
    yprimitive(i,i)=ydata(i,4);
    if (ydata(i,5)~= 0);
       j=ydata(i,5);
       ymutual=ydata(i,6);
       yprimitive(i,j)=ymutual;
    end
end
buses=max(max(ydata(2,:)),max(ydata(3,:)));
A=zeros(elements,buses);
for i=1:elements;
    if ydata(i,2)~=0;
       A(i,ydata(i,2))=1;
    end
    if ydata(i,3)~=0;
       A(i,ydata(i,3))=-1;
    end   
end
YBUS=A'*yprimitive*A;
disp('Y bus matrix is:');
disp(YBUS);