TY  - JOUR
AU  - S. Tymowski
TI  - On the analogue of the formula cos \(t = \frac{1}{2} e^{it} + \frac{1}{2} e^{-it}\) for operator cosine functions
JO  - Commentationes Mathematicae
PY  - 1983
SP  -  173
EP  - 182
VL  - 23
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.14708/cm.v23i1.6051/
DO  - 10.14708/cm.v23i1.6051
LA  - pl
ID  - 10_14708_cm_v23i1_6051
ER  -