For the element above, the values for u at each of the four nodes listed

sequentially above are $1\mathrm{.}6,2\mathrm{.}2,3\mathrm{.}1,$ and $4\mathrm{.}0.$ Find the values of x$,$ y$,$ u$,$ and the

gradient of u at the centroid $(\backslash$xi $=0,\backslash$eta $=0).$ Answers for the gradient: $0\mathrm{.}0706,0\mathrm{.}3587.$

Note that this will require computation of $[$J$],$ J$,$ and $[$J$]-1.$