Maybe I missed the numerical methods books in the textbook forum? But I'd like a few suggestions on good texts that are descriptive in implementing numerical algorithms like root-finding, numerical integration, numerical interpolation, etc. I was about to buy Numerical Recipes But I noticed in the comments that the algorithms are copyrighted.. so it's straight-up illegal to use that book in practice. There's hundreds of numerical methods books on amazon, can someone suggest one that they found useful? I have my undergrad book, which is TOO undergrad. I also have many books on FEM and numerical linear algebra, so I'm looking for one that covers a more general swath of topics. It must give detailed theory of stability, convergence, etc.