toms470, a Fortran77 code which implements ACM toms algorithm 470, for solving a linear system with an almost tridiagonal matrix.
The text of many ACM TOMS algorithms is available online through ACM: https://www.acm.org/pubs/calgo or NETLIB: https://www.netlib.org/toms/index.html.
The information on this web page is distributed under the MIT license.
toms470 is available in a Fortran77 version.