Fast and accurate algorithm for computing tensor CBR anisotropy

Inflation gives rise to a nearly scale-invariant spectrum of tensor perturbations (gravitational waves); their contribution to the cosmic background radiation (CBR) anisotropy depends upon the present cosmological parameters as well as inflationary parameters. The analysis of a sampling-variance-limited CBR map offers the most promising means of detecting tensor perturbations, but will require evaluation of the predicted multipole spectrum for a very large number of cosmological parameter sets. We present accurate polynomial formulas for computing the predicted variance of the multipole moments in terms of the cosmological parameters Omega(Lambda), Omega(o)h(2), Omega(B)h(2), N-v, and the power-law index n(T) Which are accurate to about 1% for l less than or equal to 50 and to better than 3% for 50<l less than or equal to 100 (as compared to the numerical results of a Boltzmann code).