SphereOPtimzie provides a simple tool for numerical optimization on the unit sphere. This is achieved by combining the spherical coordinating transformation with L-BFGS-B optimization algorithm. This optimization scheme is implemented in https://doi.org/10.1016/j.jspi.2020.07.001.
SphereOptimize from Github:devtools::install_github("xieyj17/SphereOptimize")
SphereOptimize from Github:Currently under review process.