opt = optimset (...)         - manipulate m*tlab-style options structure

This function returns a m*tlab-style options structure that can be used
with the fminunc() function.

INPUT : Input consist in one or more structs followed by option-value
pairs. The option that can be passed are those of m*tlab's 'optimset'.
Whether fminunc() accepts them is another question (see fminunc()).

Two extra options are supported which indicate how to use directly octave
optimization tools (such as minimize() and other backends):

"MinEquiv", [on|off] : Tell 'fminunc()' not to minimize 'fun', but
instead return the option passed to minimize().

"Backend", [on|off] : Tell 'fminunc()' not to minimize 'fun', but
instead return the [backend, opt], the name of the
backend optimization function that is used and the
optional arguments that will be passed to it. See
the 'backend' option of minimize().