This an implementation of R-matrix theory as summarized by Lane and Thomas. The emphasis of this implementation is on beta- and gamma decay experiments. ORM provides the following capabilities: A commandline interface A library for performing R-matrix calculations An open code structure that encourages extension Fast routines for calculating the penetrability and shift function. See this note. Accurate calculations of the penetrability and shift function using the Mitchel routines. Implementation for gamma-decays to unbound states. Extensive unit tests of all functionality

{"references": ["A. M. Lane and R. G. Thomas, Rev. Mod. Phys. 30 257 (1958)", "Jonas Refsgaard, Efficient and accurate approximation of R-matrix functions"]}