matrix dimensions must agree error

Hello guys, I am trying to do this problem, but ı get matrix dimensions must agree error. Can you please help me with that?

a=0;
b=4;
ca=1;
cb=-3;
a1=@(x) 0.*x;
a0=@(x) (1+x);
g=@(x) 1-x.^2;
h=0.01;
N=round((b-a)/h);
x=linspace(a,b,N+1);
x=x';
G=g(x);
K=1/h^2*(2.*diag(ones(1,N+1))-diag(ones(1,N)-1)-diag(ones(1,N),1)); % heres the error 'Matrix dimensions must agree.'
A=diag(a0(x));
A(1,1)=0;
A(end,end)=0;
A1=a1(x);
B=1/(2*h)*(diag(A1(1:end-1),1)-diag(A1(2:end),-1));
B(1,2)=0;
B(end,end-1)=0;
G(1)=ca;
G(end)=cb;
K(1,1)=1;
K(1,2)=0;
K(end,end-1)=0;
K(endd,end)=1;
y=(K+B+A)\G;

Answer 1

[Matt J]

Possibly a missing comma here,

K=1/h^2*(2.*diag(ones(1,N+1))-diag(ones(1,N)-1)-diag(ones(1,N),1)); 
                                            ^
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[Matt J]

Also, a typo in this line

K(endd,end)=1;

[Alicia G]

thanks!! i didn't see that :)