The files inst/include/integration/GaussKronrodNodesWeights.h inst/include/integration/Integrator.h were modified from library NumericalIntegration (https://github.com/tbs1980/NumericalIntegration, MPL-2) written by Sreekumar T. Balan, Matt Beall, and Mark Sauder. The files inst/include/optimization/lbfgs.h src/arithmetic_ansi.h src/lbfgs.c contained in RcppNumerical (< 0.3-0) were copied from the libLBFGS library (https://www.chokkan.org/software/liblbfgs/, MIT) written by Naoaki Okazaki. The files inst/include/integration/cuba.h src/Cuhre.c src/cuhre/* were modified from the Cuba library (https://feynarts.de/cuba/, LGPL-3) written by Thomas Hahn. The code for numerical integration on infinite intervals was contributed by Ralf Stubner . Other part of this package was written by Yixuan Qiu.