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Sunday, May 26, 2013


( The INEXACT flag mandated by IEEE Standard 754 for Binary Floating–Point Arithmetic would, if MATLAB granted us access to that flag, help us discriminate between solutions x that are exactly right and those, perhaps arbitrarily wrong, whose residuals vanish by accident.) -

Useful commands

du -sh /private/var/vm/sleepimage

Friday, May 3, 2013

Not having to specify DYLD_LIBRARY_PATH for your app when using Intel TBB (on Darwin/Mac OS X)

When using Intel Threading Building Blocks,  you have to link against their dynamic library. They do not provide a way for static linking, because when dynamic linking is used, their library has a shared state and they use that to prevent contention from over-threading.

However, the only way they provide to load their library at run-time is by having to provide a path to their library (libtbb.dylib) through the
DYLD_LIBRARY_PATH environment variable. Before your application launches you are going to have to set it in the shell. They provide a handy script to do it for you too. It may be inconvenient but it is doable (especially in non-production environments like scientific experiments).

However, although Valgrind is able to load their library correctly (and therefore run your program), GDB (7.5) can not do it. I am not able to debug my program because GDB says it can not load libtbb and dies.

So I used my Google-fu and found a solution. Just run the following command in the tbb/lib directory:

$ install_name_tool -id /absolute/path/to/libtbb.dylib libtbb.dylib

There you go. The difference is that without doing it, LD linker only puts the library name in the binary. I.e., otool -L shows only libtbb.dylib, no path, no nothing. After the command, LD puts the absolute path, and therefore it gets encoded in the binary; no need for DYLD_LIBRARY_PATH again.

I found the useful information at