Here is this guy's function copy-pasted on a SO question: https://stackoverflow.com/questions/17913191/using-typedef-in-class-for-its-own-struct-data https://s

Here is this guy's function copy-pasted on a SO question: https://stackoverflow.com/questions/17913191/using-typedef-in-class-for-its-own-struct-data https://stackoverflow.com/questions/17913191/using-typedef-i... Found it after 5 mins and a couple tweaks to the search terms. Another: https://vdoc.pub/documents/direct-methods-for-sparse-linear-systems-26b50n39j9ig https://vdoc.pub/documents/direct-methods-for-sparse-linear-... Someone copied this guy's book and put it on scribd: https://www.scribd.com/document/514019650/Direct-Methods-for-Sparse-Linear-Systems-by-Timothy-a-Davis https://www.scribd.com/document/514019650/Direct-Methods-for... Someone put it on a "personal" edu page: https://people.sc.fsu.edu/~jburkardt/c_src/csparse/csparse.c https://people.sc.fsu.edu/~jburkardt/c_src/csparse/csparse.c A modified version of it here marked as open-source: https://github.com/rwl/CSparse.py/blob/master/csparse.py https://github.com/rwl/CSparse.py/blob/master/csparse.py More: https://tonus.pages.math.unistra.fr/schnaps/schnaps/csparse_8c_source.html https://tonus.pages.math.unistra.fr/schnaps/schnaps/csparse_... Google search used to find them: https://www.google.com/search?q=Sparse+matrix+addition+%22check+inputs%22+cs_add https://www.google.com/search?q=Sparse+matrix+addition+%22ch... Could probably find more if I looked harder. Side note, looks like in a lot of places people do the ""proper""-ish thing and leave this guy's name on the code.