%%% Silly rounding error

Try out the following code:

\beginverbatim
beginfig(1);
65 = 195*1/3;
endfig;
\endverbatim

Metapost will give you an error!

\beginverbatim
! Inconsistent equation (off by -0.00099).
\endverbatim

This error is caused by accumulated rounding errors. In fact, even

\beginverbatim
show 1=3*1/3;
\endverbatim

would already report false.

The fraction $1/3$ is internally represented as $21845/65536$, and
three times that is $65535/65536$, one short of the mark (btw, most
fractional numbers detoriate faster than $1/3$). If you create the
error 65 times, you end up with a deviation of $65/65536$, and that
is what triggers the `inconsistent equation' error handler.

What makes this particularly funny is that the web source says:

\beginverbatim
if abs(value(p))>64 then {off by .001 or more}
begin print_err("Inconsistent equation");@/
print(" (off by "); print_scaled(value(p)); print_char(")");
help2("The equation I just read contradicts what was said before.")@/
  ("But don't worry; continue and I'll just ignore it.");
put_get_error;
end
\endverbatim

But the $65/65536 = 0.0009918212890625$, not $0.001$
