RElt
calculates overlap, kinetic integrals for numerical atomic orbitals.
.... For calculation of the integral over the rectangle any adaptive algorithm can be applied. The exemplary results were obtained by application of the adaptive Gauss quadrature.
The implemented algorithm is described in my paper: "Numerical calculation of overlap and kinetic integrals in prolate spheroidal coordinates", International Journal of Quantum Chemistry, Volume 108, Issue 2, Year 2008, Pages 249–256
http://onlinelibrary.wiley.com/doi/10.1002/qua.21485/full