#218 severe radcan bug

closed
nobody
None
5
2005-02-14
2003-01-29
No

the following exhibits a bug (probably) in radcan

(C1) p(u,k):=u^(-1)+u^k;
(C1)
- 1 k
(D1) p(u, k) := u + u
(C2) p1(u,k):=at(diff(p('u,k),'u),['u=u]);

(D2) p1(u, k) := AT(DIFF(p('u, k), 'u), ['u = u])
(C3) p2(u,k):=at(diff(p('u,k),'u,2),['u=u]);

(D3) p2(u, k) := AT(DIFF(p('u, k), 'u, 2), ['u = u])
(C4) tau:subst(solve(p1(u,k),u),u);

Is k an integer?

y;
1
(D4) ------
1
-----
k + 1
k
(C5) radcan(p(tau,k)/p2(tau,k));

                k + 1

(D5) --------------------------
k + 3 2
----- -----
k + 1 k + 1 2
2 k + k (k - k)
------ which is correct ----------------------------------------------------

(C6) radcan(sqrt(%));

              SQRT\(k + 1\)

(D6) -------------------
1
-----
k + 1 2
k SQRT(k + k)

------- which is bogus, evaluate D5 and D6 at k=2 for example ------

(C7) bug_report();

The Maxima bug database is available at
http://sourceforge.net/tracker/?atid=104933&group_id=4933&func=browse
Submit bug reports by following the 'Submit New' link on that page.
Please include the following build information with your bug report:
-------------------------------------------------------------

Maxima version: 5.9.0rc3
Maxima build date: 21:0 11/26/2002
host type: i686-pc-linux-gnu
lisp-implementation-type: Kyoto Common Lisp
lisp-implementation-version: GCL-2-5.0

-------------------------------------------------------------
The above information is also available from the Maxima function
build_info().

maybe this is related to bug no 635338:
http://sourceforge.net/tracker/index.php?func=detail&aid=635338&group_id=4933&atid=104933

Discussion

  • Viktor Toth

    Viktor Toth - 2004-04-21

    Logged In: YES
    user_id=1023504

    I don't see the bug here, the result appears to be correct
    actually. D6 is the square root of the D5 expression, which
    is what it should be, or am I missing something?

    Viktor

     
  • Martin Rubey

    Martin Rubey - 2004-05-11

    Logged In: YES
    user_id=651552

    Sorry, it seems that I'm really stupid. I cannot see a bug
    here either.

    Excuse me, please,

    Martin Rubey

     
  • Stavros Macrakis

    • status: open --> closed
     

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