matlab - Index exceeds matrix dimensions -

i wrote code that:

for inode=1:8    ielem=1:nelem       ipoin=abs(lnods(ielem,inode));       k=1:3          gtop=coordi(ipoin,k);          gbot=coordi(ipoin,k+4);          gosh=((1.0+0.91)*gtop+(1.0-0.91)*gbot)/2.0;          j=1:3             wormx(k,j)=wormx(k,j)+gosh*shape(j,inode);  <----error          end          wormx(k,4)=wormx(k,4)+shape(1,inode)*(gtop-gbot)/2.0;        end    end end 

i got error 'index exceeds matrix dimensions' lnods 9 9 matrix, nelem 9, inode 1, , coordi 49 by8 matrix.