BLAS Level 1 operations in Octave

[Marco Caliari]

Dear maintainers,

my octave-4.1.0+ is linked to multithreaded ATLAS libraries. They work as 
expected: in particular, a matrix-matrix product involves all my four 
cores (top shows %CPU at about 390). But, if I run the following script

a = rand(200000,1);
b = rand(200000,1);
tic
for i = 1:100000
    c = a+b; % version 1
%    b = a+b; % version 2
%    b += a; % version 3
end
toc

my %CPU is stuck to 100, (while Matlab, linked to Intel MKL, uses again 
all the four cores). Versions 2 and 3 are a *axpy (BLAS Level 1) 
operation, while version 1 is a *copy followed by a *axpy operation. 
Anyway, they should be multithread in ATLAS, so I presume Octave does not 
use them. In fact, a

grep -r --include "*" AXPY

in the sources shows something only is some cruft fortran files. At the 
moment, I cannot check the behavior of OpenBLAS libraries.

Since "it might be a worthy goal, after the 4.2 release, to look at 
improving Octave's performance", is this a possible topic to be 
investigated?

Regards,

Marco