A large list of C/C++ Sources for Numerical Computation, as its' website introduces:
This is a collection of pointers to:

* free source code available on the net,
* books which come with source code, and hence act as low-cost libraries,
* articles and documents, especially those available over the net.

Check it out if you happen to find it useful: http://cliodhna.cop.uop.edu/~hetrick/c-sources.html
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