Aloc=0.25*[1 -1;-1 1] Aloc = 0.25000000000000 -0.25000000000000 -0.25000000000000 0.25000000000000 format short Aloc=[1 -1;-1 1] % we'll multiply the result by 1/4 later Aloc = 1 -1 -1 1 ien=[1:4;2:5] ien = 1 2 3 4 2 3 4 5 A=zeros(5) A = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e=1,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc e = 1 i = 1 2 Ae = 1 -1 0 0 0 -1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e=1,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc, A=A+Aloc e = 1 i = 1 2 Ae = 1 -1 0 0 0 -1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ??? Error using ==> plus Matrix dimensions must agree. e=1,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc, A=A+Ae e = 1 i = 1 2 Ae = 1 -1 0 0 0 -1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A = 1 -1 0 0 0 -1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e=2,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc, A=A+Ae e = 2 i = 2 3 Ae = 0 0 0 0 0 0 1 -1 0 0 0 -1 1 0 0 0 0 0 0 0 0 0 0 0 0 A = 1 -1 0 0 0 -1 2 -1 0 0 0 -1 1 0 0 0 0 0 0 0 0 0 0 0 0 e=3,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc, A=A+Ae e = 3 i = 3 4 Ae = 0 0 0 0 0 0 0 0 0 0 0 0 1 -1 0 0 0 -1 1 0 0 0 0 0 0 A = 1 -1 0 0 0 -1 2 -1 0 0 0 -1 2 -1 0 0 0 -1 1 0 0 0 0 0 0 e=4,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc, A=A+Ae e = 4 i = 4 5 Ae = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 -1 0 0 0 -1 1 A = 1 -1 0 0 0 -1 2 -1 0 0 0 -1 2 -1 0 0 0 -1 2 -1 0 0 0 -1 1 A=0.25*A A = 0.2500 -0.2500 0 0 0 -0.2500 0.5000 -0.2500 0 0 0 -0.2500 0.5000 -0.2500 0 0 0 -0.2500 0.5000 -0.2500 0 0 0 -0.2500 0.2500 A=zeros(3) A = 0 0 0 0 0 0 0 0 0 A=zeros(5) A = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e=4,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc; Ae(:,1)=0; Ae(1,:)=0;Ae(5,:)=0;Ae(:,5)=0;Ae A=A+Ae ??? Error: "Ae" was previously used as a variable, conflicting with its use here as the name of a function. e=4,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc; Ae(:,1)=0; Ae(1,:)=0;Ae(5,:)=0;Ae(:,5)=0; A=A+Ae e = 4 i = 4 5 A = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 e=4,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc; Ae(:,1)=0; Ae(1,:)=0;Ae(5,:)=0;Ae(:,5)=0; A=A+Ae e = 4 i = 4 5 A = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 A=zeros(5) A = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e=1,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc; Ae(:,1)=0; Ae(1,:)=0;Ae(5,:)=0;Ae(:,5)=0; A=A+Ae e = 1 i = 1 2 A = 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ae Ae = 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e=2,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc; Ae(:,1)=0; Ae(1,:)=0;Ae(5,:)=0;Ae(:,5)=0; A=A+Ae e = 2 i = 2 3 A = 0 0 0 0 0 0 2 -1 0 0 0 -1 1 0 0 0 0 0 0 0 0 0 0 0 0 e=3,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc; Ae(:,1)=0; Ae(1,:)=0;Ae(5,:)=0;Ae(:,5)=0; A=A+Ae e = 3 i = 3 4 A = 0 0 0 0 0 0 2 -1 0 0 0 -1 2 -1 0 0 0 -1 1 0 0 0 0 0 0 e=4,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc; Ae(:,1)=0; Ae(1,:)=0;Ae(5,:)=0;Ae(:,5)=0; A=A+Ae e = 4 i = 4 5 A = 0 0 0 0 0 0 2 -1 0 0 0 -1 2 -1 0 0 0 -1 2 0 0 0 0 0 0 e=4,Ae=zeros(5);i=ien(:,e),Ae(i,i)=Aloc; Ae(:,1)=0; Ae(1,:)=0;Ae(5,:)=0;Ae(:,5)=0; A=A+Ae e = 4 i = 4 5 A = 0 0 0 0 0 0 2 -1 0 0 0 -1 2 -1 0 0 0 -1 3 0 0 0 0 0 0 diary off