We introduce a map, operating on the cone of lower semicontinuous convex functionals, which extends the Logarithm from positive invertible operators to convex functionals. Afterwards, we present a second order functional limited development extending that of operators. The paper will be illustrated with some examples which justify the chosen terminology and the importance of this work.

Contact details are reproduced from the original publication and may be historical.

Mustapha Raïssouli

Groupe AFA - UFR AFACS, Université Moulay Ismaïl, Faculté des Sciences, Dép. de
Mathématiques et Informatique, BP 4010, Zitoune, Meknés, Maroc

raissoul@fsmek.ac.ma

Hanane Bouziane

Groupe AFA - UFR AFACS, Université Moulay Ismaïl, Faculté des Sciences, Dép. de
Mathématiques et Informatique, BP 4010, Zitoune, Meknés, Maroc

  1. M. Atteia, M. Raïssouli: Self dual operators on convex functionals; geometric mean and square root of convex functionals, J. Convex Anal. 8 (2001) 223–240.https://doi.org/10.68381/jca08010Google Scholar
  2. J. P. Aubin: Analyse non Linéaire et ses Motivations Économiques, Masson (1981).Google Scholar
  3. H. Brezis: Operateurs Maximaux Monotones et Semi-Groupes de Contractions dans les Espaces de Hilbert, North-Holland (1973).Google Scholar
  4. J. I. Fujii: Arithmetico-geometric means of operators, Math. Japonica 23 (1979) 667–669.Google Scholar
  5. J. I. Fujii, M. Fujii: On geometric and harmonic means of positive operators, Math. Japonica 24 (1979) 203–207.Google Scholar
  6. B. W. Helton: Logarithms of matrices, Proc. Amer. Math. Soc. 19 (1968) 733–738.https://doi.org/10.1090/S0002-9939-1968-0227197-2Google Scholar
  7. J. B. Hiriart-Urruty: How to regularize a difference of convex functions, J. Math. Anal. Appl. 162 (1991) 196–209.https://doi.org/10.1016/0022-247X(91)90187-5Google Scholar
  8. J. J. Moreau : Proximité et dualité dans un espace hilbertien, Bull. Soc. Math. France 93 (1965) 273–299.https://doi.org/10.24033/bsmf.1625Google Scholar
  9. R. D. Nussbaum, J. E. Cohen: The arithmetic-geometric mean and its generalizations for noncommuting linear operators, Ann. Sci. Norm. Sup. Sci. IV 15(2) (1989) 239–308.Google Scholar
  10. M. Raïssouli, H. Bouziane: Second order approximation of a Fenchel conjugate in convex analysis, Journal of Optimization Theory and Applications, to appear.Google Scholar
  11. M. Raïssouli, M. Chergui: Arithmetico-geometric and geometrico-harmonic means of two convex functionals, Scientiae Mathematicae Japonicae 5 (2001), to appear.Google Scholar
  12. L. Schwartz: Analyse Hilbertienne, Hermann (1979).Google Scholar
  13. A. Seeger: Degree of pointedness of a convex function, Bull. Austral. Math. Soc. 53 (1996) 159–167.https://doi.org/10.1017/S000497270001683XGoogle Scholar

M. Raïssouli, H. Bouziane. “Functional Logarithm in the Sense of Convex Analysis.” Journal of Convex Analysis 10 (2003), No. 1, 229–244. https://doi.org/10.68381/jca1012