SourceForge has been redesigned. Learn more.
Close

#1829 integration failure with option integrate_use_rootsof :true

closed
nobody
5
2009-12-01
2009-11-30
Anonymous
No

(%i12) integrate_use_rootsof : true;
(%i13) -pt*integrate((d*QA^2+2*c*QA+3*b)/(g*QA^3*R+d*QA^2+c*QA+b),QA);
Maxima encountered a Lisp error:
Error in PROGN [or a callee]: Caught fatal error [memory may be damaged]
Automatically continuing.
To reenable the Lisp debugger set *debugger-hook* to nil.

Discussion

  • Dieter Kaiser

    Dieter Kaiser - 2009-11-30

    I think the bug is in the routine integrate-use-rootsof:

    (defun integrate-use-rootsof (f q variable &aux qprime ff qq (dummy (make-param)) lead)
    ;; p2e is squarefree polynomial in cre form, p1e is lower degree
    (setq lead (p-lc q)) <--- Problem
    (setq qprime (disrep (pderivative q (p-var q))))
    (setq ff (disrep f) qq (disrep q))
    `((%lsum) ((mtimes)
    ,(div* (mul* lead (subst dummy variable ff))
    (subst dummy variable qprime))
    ((%log) ,(sub* variable dummy))) ,dummy
    (($rootsof) ,qq)))

    There is no DISREP for the leading coefficient of q, but for the example of this bug report we get an CRE expression as a coefficient. When we do a DISREP

    (setq lead (disrep (p-lc q)))

    the integral of this bug report will work:

    (%i4) integrate_use_rootsof : true;
    (%o4) true
    (%i5) integrate((d*QA^2+2*c*QA+3*b)/(g*QA^3*R+d*QA^2+c*QA+b),QA);
    (%o5) 'lsum((%r2^2*d+2*%r2*c+3*b)*g*log(QA-%r2)*R/(3*%r2^2*g*R+2*%r2*d+c),%r2,
    rootsof(g*QA^3*R+d*QA^2+c*QA+b))

    The testsuite has no examples for this type of integrals, but the example of the documentation will work as expected with this change.

    Dieter Kaiser

     
  • Dieter Kaiser

    Dieter Kaiser - 2009-12-01

    Fixied in sinint.lisp revision 1.9.
    Closing this bug report as fixed.
    Dieter Kaiser

     
  • Dieter Kaiser

    Dieter Kaiser - 2009-12-01
    • status: open --> closed
     

Log in to post a comment.