  A high-precision two-dimensional stellar evolution code has been developed
for studying solar variability due to structural changes produced by varying
internal magnetic fields of arbitrary configurations. Specifically, we are
interested in modeling the effects of a dynamo-type field on the detailed
internal structure and on the global parameters of the Sun. The high precision
is required both to model very small solar changes (of order of $10^{-4}$) and
short time scales (or order of one year). It is accomplished by using the mass
coordinate to replace the radial coordinate, by using fixed and adjustable time
steps, a realistic stellar atmosphere, elements diffusion, and by adjusting the
grid points. We have also built into the code the potential to subsequently
include rotation and turbulence. The current code has been tested for several
cases, including its ability to reproduce the 1-D results.
