24 Oct
2011
24 Oct
'11
11:31 a.m.
On 24 Oct 2011 at 10:42, Fred Cisin wrote:
On "REAL"s, it is a STRUGGLE to get them to
understand that it is NOT
an "ERRORS!" when an approximation is not exact. One exercise that
helps a little is to make them divide 1 by 3; write down the result;
TURN OFF the calculator; multiply whatever they wrote down by 3; and
then EXPLAIN the "ERRORS!".
Or that "arithmetic" doesn't work.
a+b+b+b+b+b+b is not the same as
a+6.*b
and so forth. If the magnitudes of a and b are sufficiently
different, the result of the first may well be a; while the second
will be something other than a.
Trigonometric functions are in a world of their own. Woe to the
programmer that thinks that acos() always returns values with the
same accuracy across the full range of arguments.
--Chuck