'C++' Reimplementation of the 'ucminf' Unconstrained Nonlinear Optimizer // A modern 'C++17/ reimplementation of the 'UCMINF/ algorithm for unconstrained nonlinear optimization (Nielsen and Mortensen, 2011, doi:10.32614/CRAN.package.ucminf), offering full API compatibility with the original 'ucminf' R package but developed independently. The optimizer core has been rewritten in 'C' with a modern header-only 'C++17' interface, zero- allocation line search, and an 'Rcpp' interface. The goal is numerical equivalence with improved performance, reproducibility, and extensibility. Includes extensive test coverage, performance regression tests, and compatibility checks against 'ucminf'. This package is not affiliated with the original maintainers but acknowledges their authorship of the algorithm and the original R interface.