We study a method to solve stationary axisymmetric vacuum Einstein equations
numerically. As an illustration, the five-dimensional doubly spinning black
rings that have two independent angular momenta are formulated in a way
suitable for fully nonlinear numerical method. Expanding for small second
angular velocity, the formulation is solved perturbatively upto second order
involving the backreaction from the second spin. The obtained solutions are
regular without conical singularity, and the physical properties are discussed
with the phase diagram of the reduced entropy vs the reduced angular momenta.
Possible extensions of the present approach to constructing the higher
dimensional version of black ring and the ring with the cosmological constant
are also discussed.Comment: 20 pages, 6 figure