  The confrontation of the Cosmic Microwave Background (CMB) theoretical
angular power spectrum with available data often requires the calculation of
large numbers of power spectra. The standard practice is to use a fast code to
compute the CMB power spectra over some large parameter space, in order to
estimate likelihoods and constrain these parameters. But as the dimensionality
of the space under study increases, then even with relatively fast anisotropy
codes, the computation can become prohibitive. This paper describes the
employment of a "morphing" strategy to interpolate new power spectra based on
previously calculated ones. We simply present the basic idea here, and
illustrate with a few examples; optimization of interpolation schemes will
depend on the specific application. In addition to facilitating the exploration
of large parameter spaces, this morphing technique may be helpful for Fisher
matrix calculations involving derivatives.
