Everything in the objective function other than p is input data.
y and a is 10 * 1 vector.
A is 10 * 1800 array.
matrix_frac Matrix fractional function. matrix_frac(x,Y), where Y is a square matrix and x is a vector of the same size, computes x'*(inv(Y)*x) if Y is Hermitian positive definite, and +Inf otherwise. An error results if Y is not a square matrix, or the size of the vector x does not match the size of matrix Y. Disciplined convex programming information: matrix_frac is convex and nonmonotonic (at least with respect to elementwise comparison), so its argument must be affine.