Towards a gauge-polyvalent numerical relativity code

The gauge polyvalence of a new numerical code is tested, both in harmonic-coordinate simulations (gauge-waves test bed) and in singularity-avoiding coordinates (simple black-hole simulations, either with or without shift). The code is built upon an adjusted first-order flux-conservative version of the Z4 formalism and a recently proposed family of robust finite-difference high-resolution algorithms. An outstanding result is the long-term evolution (up to 1000M) of a black hole in normal coordinates (zero shift) without excision.