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+--- Thread: conjugate issue (/thread-5248.html)
conjugate issue - ji3m - 12-01-2015 05:48 PM
In my program i build a string like
s := "conj (2+3*i)" and then do
r := CAS (s);
the returned r is 2-3*i with a funny looking minus sign.
But then
t := "conj (" + r + ")" gives t := "conj (2-3*i)"
But the CAS (t) fails with a major error.
At the cas window , when rentering the item with the odd minus
sign it is converted by the parser to a normal minus sign so it works.
This program shows my problem better.
Enter bbb (2+3*i) or even bbb ("2+3*i") .
It fails when trying to use return result Q (whick has funky minus sign)
EXPORT bbb(S)
BEGIN
LOCAL P,Q,R,T;
DEBUG;
P := "conj(" + S + ")";
Q := CAS(P);
R := "conj(" + Q + ")"; // using STRING (Q) doesnt help
T := CAS(R); // fails here
END;
RE: conjugate issue - Han - 12-01-2015 08:03 PM
(12-01-2015 05:48 PM)ji3m Wrote: In my program i build a string like
s := "conj (2+3*i)" and then do
r := CAS (s);
the returned r is 2-3*i with a funny looking minus sign.
But then
t := "conj (" + r + ")" gives t := "conj (2-3*i)"
But the CAS (t) fails with a major error.
At the cas window , when rentering the item with the odd minus
sign it is converted by the parser to a normal minus sign so it works.
This program shows my problem better.
Enter bbb (2+3*i) or even bbb ("2+3*i") .
It fails when trying to use return result Q (whick has funky minus sign)
EXPORT bbb(S)
BEGIN
LOCAL P,Q,R,T;
DEBUG;
P := "conj(" + S + ")";
Q := CAS(P);
R := "conj(" + Q + ")"; // using STRING (Q) doesnt help
T := CAS(R); // fails here
END;
This looks like a bug in the "minus" sign that conj() returns. It looks a lot like a negation symbol. Manually copying the result from CAS view changes it to the correct subtraction sign. However, using string conversion seems to keep the invalid character. I wonder if this is an XCAS issue...
RE: conjugate issue - ji3m - 12-01-2015 08:19 PM
Finaly a bug that's not just a my own mis-understanding.
My work-around:
If type(q) ==DOM_COMPLEX
then
s:= string (RE (s)) + "+" + string (IM (s)) + "*i ";
end;
s will be uzed in a cas string.It works nicely.
So IM(s) gets a normal minus or evaluates the negation.