[GiNaC-devel] [SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-406-g9ada7a7

[Alexei Sheplyakov]

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- Log -----------------------------------------------------------------
commit 9ada7a7f5c47e512b7bf6057d4c013612be9a33b
Author: Matthias Dellweg <dellweg at tp1.uni-duesseldorf.de>
Date:   Tue Dec 10 10:55:28 2013 +0200

    expairseq::match(): no side effects if match failed. Fixes spurious match failures.
    
    > match(sin(y)*exp(b)+sin(x)*exp(a), sin($0)*exp(a)+exp(b)*sin($1))
    FAIL
    
    The reason is that expairseq::match() might assign a wildcard even if
    the match fails. The first attempted submatch is sin(y)*exp(b) with
    sin($0)*exp(a). It fails (as it should) but $0 == y gets assigned as
    a side effect (which is wrong). Next submatch is sin(x)*exp(a) with
    sin($0)*exp(a) (the same pattern as in the first submatch). This one
    fails because of spurious $0 == y assignment.
    
    Due to the unpredicatable term ordering the sequence of submatches might
    be different and the match might succeed (as it should). This makes
    debugging a bit more funny.
    
    Signed-off-by: Matthias Dellweg <dellweg at tp1.uni-duesseldorf.de>
    
    [Alexei Sheplyakov: figure out the cause of the problem, make a test case]

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

Summary of changes:
 check/match_bug.cpp |   44 ++++++++++++++++++++++++++++++++++++++++++++
 ginac/expairseq.cpp |   26 +++++++++++++++++++++-----
 2 files changed, 65 insertions(+), 5 deletions(-)


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GiNaC -- a C++ library for symbolic computations