integrate and probably other functions don't handle floats in
expressions very well, so the keepfloat flag causes trouble for them.
Can we straighten things out by doing away with keepfloat? Or should we
try to fix the bugs in integrate & elsewhere? E.g. maybe we can fix all
such bugs by substituting symbols for floats, carrying out the
calculation, then substituting again at the end. I suppose that could
change the result in unpredictable ways -- integrate might succeed with
a number but not a symbol, or vice versa -- but maybe that's preferable
to running into an error.
Bug report [1] is the immediate motivation for this message, although
we've known about such problems for a long time.
best,
Robert Dodier
[1] http://sourceforge.net/p/maxima/bugs/2510/