fix precision in findroot: set tol a bit bigger than eps; convert starting points to mpmath numbers
fix precision in findroot: set tol a bit bigger than eps; convert starting points to mpmath numbers

JensGrabner/mpmath,klkuhlm/mpmath,klkuhlm/mpmath,bjodah/mpmath,bjodah/mpmath,fredrik-johansson/mpmath,JensGrabner/mpmath