[Octave-bug-tracker] [bug #49667] Computing powers of complex numbers in 4.2.0 is slower than in 4.0.3

[Mike Miller]

Update of bug #49667 (project octave):

              Item Group:              Regression => Performance            
                  Status:                    None => Need Info              

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Follow-up Comment #1:

If it's only a problem on Ubuntu 14.04 / Mint 17, then it looks like you are
arguing that it's not an Octave bug. It's very possible that some of the C++11
math functions that we started using in 4.2 have some problems with an older
toolchain of gcc/libc/libm/libstdc++. Maybe using perf or valgrind
--tool=callgrind can help shed some light on what underlying library calls are
different for you between 4.0 and 4.2. That might help demonstrate that it is
the system libraries to blame for the performance difference, not necessarily
that we may do anything about this in Octave.

For what it's worth, on Debian with gcc 6 and glibc 2.24, I get just about
identical performance between 3.6.4 and 4.2.0.

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