What are some classic mathematics-focused programming books from the 1960s–1980s?

The 1986 edition of Numerical Recipes by Press and Flannery is a strong choice. It was originally written in FORTRAN, and the explanations develop algorithms directly from the underlying equations, so there’s very little abstraction between the mathematics and the code. Mathematical Methods for Digital Computers by Ralston, from 1967, is another worthwhile reference, especially for algorithms intended to run directly on early hardware. Searching older catalogs for combinations like “numerical analysis” and “programming” can also uncover useful titles.

Knuth’s The Art of Computer Programming is an obvious but excellent recommendation. It covers fundamental algorithms, mathematical analysis, data structures, and low-level implementation details in considerable depth. It can be demanding, but it’s ideal if you want to understand why the algorithms work rather than just copy an implementation.

You may also want to look through older technical books and magazines connected to electronics or embedded systems. Collections from the BYTE era and similar publications often had articles on floating-point formats, binary arithmetic, CRCs, and practical numerical algorithms. Older embedded-systems journals can be particularly useful because they tended to publish code that had been tested on real, resource-constrained machines.