This paper is concerned with nonlinear optimization problems in normed linear spaces. Necessary and sufficient conditions for optimal points are given and the range of applicability of these conditions is studied. The results are applied to nonlinear approximation problems. © 1973.
Krabs, W. (1973). Nonlinear optimization and approximation. Journal of Approximation Theory, 9(4), 316–326. https://doi.org/10.1016/0021-9045(73)90078-6