(1) -> precision()
(1) 68
Type: PositiveInteger
(2) -> precision(300)
(2) 68
Type: PositiveInteger
(3) -> a := sqrt(2.0);
Type: Float
(4) -> precision(68)
(4) 300
Type: PositiveInteger
(5) -> a
(5)
1.4142135623_7309504880_1688724209_6980785696_7187537694_8073176679_737990732
4_7846210703_885038753
Type: Float
Is that really what one wants: I am implementing an algorithm, where I switch
internally to a higher precision to guarantee the result being correct in the
working precision.
So right now FriCAS is cheating - at least for such an algorithm
The bad guy is
convert(f):S ==
b:Integer :=
OUTPREC() = -1 and not zero? f =>
bits(length(abs mantissa f)::PositiveInteger)
0
s :=
OUTMODE() = "fixed" => fixed f
OUTMODE() = "floating" => floating f
OUTMODE() = "general" => general f
empty()$String
if b > 0 then bits(b::PositiveInteger)
s = empty()$String => error "bad output mode"
s
Here bits is called in the body of b, and here the switch to the larger
(possibly incorrect) precision occurs, and later on it is switched back to the
working precision
I think it would be a good rule to make output precision to working precision,
if a user wants to change this he has to explicitly change precision
Mit freundlichen Grüßen
Johannes Grabmeier
Prof. Dr. Johannes Grabmeier
Köckstraße 1, D-94469 Deggendorf
Tel. +49-(0)-991-2979584, Tel. +49-(0)-171-5503789
Tel. +49-(0)-991-3615-100 (d), Fax: +49-(0)-1803-5518-17745
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