[Maxima-bugs] [ maxima-Bugs-1879521 ] Sum function fails

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Bugs item #1879521, was opened at 2008-01-25 10:31
Message generated for change (Comment added) made by andrejv
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Tore Gaupseth (toregaupseth)
Assigned to: Nobody/Anonymous (nobody)
Summary: Sum function fails

Initial Comment:
Sum function fails,
sum((9/8)*(2/3)**i, i, 0, inf), simpsum;
gives answer 216 instead of 9/8=3.375

Maxima version: 5.14.0
Maxima build date: 21:46 12/27/2007
host type: i686-pc-mingw32
lisp-implementation-type: GNU Common Lisp (GCL)
lisp-implementation-version: GCL 2.6.8

(%i51) sum((5/4)*(2/3)**i, i, 0, inf), simpsum;
                                      15
(%o51)                                --
                                      4
(%i52) sum((1.25)*(2/3)**i, i, 0, inf), simpsum;
(%o52)                               3.75
(%i53) sum((9/8)*(2/3)**i, i, 0, inf), simpsum;
(%o53)                                216
(%i54) sum((1.125)*(2/3)**i, i, 0, inf), simpsum;
(%o54)                               3.375



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>Comment By: Andrej Vodopivec (andrejv)
Date: 2008-01-28 18:38

Message:
Logged In: YES 
user_id=1179910
Originator: NO

This works as expected on sbcl + cvs maxima:

(%i1) sum((9/8)*(2/3)**i, i, 0, inf), simpsum;
(%o1) 27/8
(%i2) build_info()$
Maxima version: 5.14.0cvs
Maxima build date: 23:27 1/26/2008
host type: i386-apple-darwin8.11.1
lisp-implementation-type: SBCL
lisp-implementation-version: 1.0.10

Andrej

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Comment By: Tore Gaupseth (toregaupseth)
Date: 2008-01-25 11:17

Message:
Logged In: YES 
user_id=1234122
Originator: YES

The third line should read
gives answer 216 instead of 27/8=3.375

-and maybe the fault is that a math formula gives  3^3 * (2^(-3))
and Maxima somehow calculates  3^3 * 2^3


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