[Maxima-bugs] [ maxima-Bugs-1482843 ] subscripted variable causes trouble in integrate

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Bugs item #1482843, was opened at 2006-05-05 22:55
Message generated for change (Comment added) made by rtoy
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Category: Lisp Core - Integration
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Robert Dodier (robert_dodier)
Assigned to: Nobody/Anonymous (nobody)
Summary: subscripted variable causes trouble in integrate

Initial Comment:
Maxima 5.9.3 / clisp 2.34:
-------------------------------------
OK:

(%i4) integrate (exp (- (x - mu)^2), x, 0, inf);
(%o4) sqrt(%pi)*erf(mu)/2+sqrt(%pi)/2

-------------------------------------
OOPS:
(%i3) integrate (exp (- (x - mu[1])^2), x, 0, inf);
Is  ?yx+1  positive or negative?

p;
Is  x  positive, negative, or zero?

p;
Is  mu[1]  positive or negative?

p;
(%o3)
%i*(sqrt(%pi)*%i*('limit(erf(%i*sqrt(log(x))),x,0,plus))
         +sqrt(%pi)*%i*erf(mu[1]))
       /2

-------------------------------------
Maxima 5.9.1 / cmucl 19a:
-------------------------------------
(%i7) integrate (exp (- (x - mu[1])^2), x, 0, inf);

Is  "*"(MU[1])  positive, negative, or zero?

p;
Is  "*"(ABS(%E)-1)  positive, negative, or zero?

p;
Maxima encountered a Lisp error:

 Type-error in KERNEL::OBJECT-NOT-TYPE-ERROR-HANDLER:
    ((MTIMES) 2 ((RAT SIMP) 1 2)) is not of type REAL


----------------------------------------------------------------------

>Comment By: Raymond Toy (rtoy)
Date: 2006-05-06 09:45

Message:
Logged In: YES 
user_id=28849

This bug is caused by deg-lessp in defint.lisp not handling
subscripted variables.  It returned NIL instead of T for mu[1].

With this fix, the integrand with mu[1] returns a result
like the integrand for mu.

Fixed in defint.lisp, rev 1.25.


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