This problem will demonstrate the progression of the singular value approximation using the MATLAB command "svd" in finding a singular value decomposition. A singular value decomposition diagonalizes and decomposes a matrix $A$ into three matrices, one diagonal and two orthogonal.
(a) Given
$$
A=\left[\begin{array}{llll}
4 & 0 & 0 & 0 \\
0 & 4 & 0 & 0 \\
0 & 0 & 4 & 0 \\
0 & 0 & 0 & 4
\end{array}\right]
$$
find its singular value decomposition using the MATLAB command *" $[\mathrm{U}, \mathrm{S}, \mathrm{V}]=$ $\operatorname{svd}(\mathrm{A}) . "$
(b) A matrix approximation is a summation of the products of all the singular values with their corresponding column vectors from matrices U and V as
$$
\mathrm{A}=u_1 s_1 v_1^{\mathrm{T}}+\cdots+u_n s_n v_n^{\mathrm{T}}
$$
Perform a rank $1,2,3$, and 4 approximation of the matrix in part (a).