Look at the following functions.
You might get trapped.
PP ==> PostiveInteger
C ==> Fraction Integer
expTruncated1(s: PP, t: C): C ==
z: C := 1 + t -- truncated exp
n: PP := 1 -- exponent for t
p: C := t -- power of t, p=t^n
f: C := 1 -- factorial, f=n!
while n < s repeat
n := n + 1;
p := p * t;
f := n * f;
z := z + p / f;
z
expTruncated2(s: PP, t: C): C ==
z: C := 1 + t -- truncated exp
n: PP := 1 -- exponent for t
p: C := t -- power of t, p=t^n
f: C := 1 -- factorial, f=n!
while n < s repeat
n := n + 1; p := p * t; f := n * f; z := z + p / f;
z
The expTruncated1 function behaves as expected.
The second function is not the same if the line following the "while"
keyword is enclosed in parentheses.
while n < s repeat
(n := n + 1; p := p * t; f := n * f; z := z + p / f);
Actually that is pretty clear since
while n < s repeat
n := n + 1; p := p * t; f := n * f; z := z + p / f;
and
while n < s repeat n := n + 1; p := p * t; f := n * f; z := z + p / f;
are the same according to the pile rules and then only the "n:=n+1"
belongs to the loop body and not the whole line.
So the code for expTruncated2 is OK, but somewhat hard to interpret for
the not-so-familiar eye.
Just a comment.
Ralf
--
You received this message because you are subscribed to the Google Groups "FriCAS -
computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to fricas-devel+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/fricas-devel/a6411b2f-2dfd-4088-bab1-6539f961915c%40hemmecke.org.
