  We obtain operator concavity (convexity) of some functions of two or three
variables by using perspectives of regular operator mappings of one or several
variables. As an application, we obtain, for $ 0<p < 1,$ concavity,
respectively convexity, of the Frech\'{e}t differential mapping associated with
the functions $t \to t^{1+p} $ and $t \to t^{1-p}.$
