  The implementation of global non-analytical fit is exemplified by its
application to the spectral analysis of the complex lineshape of
Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ at $(\pi,0)$. It deals with properly a
multi-level globality in the fitting parameters and efficiently the
non-analytical evaluation of the fitting function, thus exhibiting a potential
applicability to a wide range of systematic analysis task.
