• The algebra of smooth functions of rapid descent 

      Oleche, Paul O.; Ongati, Naftali O.; Agure, John O. (2009)
      A bounded operator with the spectrum lying in a compact set V ⊂ R, has C∞ (V) functional calculus. On the other hand, an operator H acting on a Hilbert space H, admits a C(R) functional calculus if H is self-adjoint. So ...
    • The algebra of smooth functions of rapid descent 

      Ongati, Naftali O.; Oleche, Paul O.; Agure, John O. (2009)
      A bounded operator with the spectrum lying in a compact set V ⊂ R, has C∞(V ) functional calculus. On the other hand, an operator H acting on a Hilbert space H, admits a C(R) functional calculus if H is self-adjoint. So ...