Solving system Ax=b in linear least squares fashion with complex elements and lower-triangular square A matrix

Question

I would like to solve the linear system Ax = b in a linear least squares fashion, thereby obtaining x. Matrices A, x and

Answer 1

Since std::complex is a template class, and you init with std::complex(1,1); the compiler doesn't know what type it is.

Use std::complex<double>(1, 1); instead.