[Numpy-discussion] compiling ATLAS for numpy

Emanuele Olivetti olivetti at itc.it
Thu Sep 28 03:18:18 CDT 2006

I'm installing numpy on a 2 cpus intel pentium 4 Linux box. I'm installing BLAS and
LAPACK from sources too and I need to tune compiler flags. Here is the question: which
are the proper flags for compiling LAPACK? Inside lapack.tgz make.inc.LINUX says:
            OPTS     = -funroll-all-loops -fno-f2c -O3
instead on scipy.org[0] it's suggested:
            OPTS = -O2

I assume that using -O3 and unrolling loops should have definitely better performance
that just -O2 but I'm wondering if the speedy options can be a problem for current
numpy release (numpy-1.0rc1). Is it safe to use '-funroll-all-loops -fno-f2c -O3'?

Thanks in advance for answers,


[0]: http://scipy.org/Installing_SciPy

P.S.: my GCC is v3.4.5

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