  We develop a practical forward fitting method based on the SIMPLEX algorithm
with shaking, which allows the derivation of the magnetic field and other
parameters along a solar flaring loop using microwave imaging spectroscopy of
gyrosynchrotron emission. We illustrate the method using a model loop with
spatially varying magnetic field, filled with uniform ambient density and an
evenly distributed fast electron population with an isotropic, power-law energy
distribution.

Solar and Stellar Astrophysics