alexei,
about formatted output, maxima 5.9.3 includes an add-on package named stringproc
which has a printf function (among many other things).
printf recognizes lisp format directives (~e, ~f, ~s, ~% etc).
in particular, ~s (equivalently, ~a) formats an arbitrary maxima object
in 1-dimensional notation. ~s is the directive to use for bigfloats
(there isn't a format directive specifically for bigfloats).
load (stringproc);
loads the package.
? printf
shows some info about printf.
hth
robert dodier