  We have developed a new three-dimensional general relativistic
magnetohydrodynamic (GRMHD) code, RAISHIN, using a conservative, high
resolution shock-capturing scheme. The numerical fluxes are calculated using
the Harten, Lax, & van Leer (HLL) approximate Riemann solver scheme. The
flux-interpolated, constrained transport scheme is used to maintain a
divergence-free magnetic field. In order to examine the numerical accuracy and
the numerical efficiency, the code uses four different reconstruction methods:
piecewise linear methods with Minmod and MC slope-limiter function, convex
essentially non-oscillatory (CENO) method, and piecewise parabolic method (PPM)
using multistep TVD Runge-Kutta time advance methods with second and
third-order time accuracy. We describe code performance on an extensive set of
test problems in both special and general relativity. Our new GRMHD code has
proven to be accurate in second order and has successfully passed with all
tests performed, including highly relativistic and magnetized cases in both
special and general relativity.
