1.NounAn operator defined as a function of the differentiation operator (the operator which maps functions to their derivatives).
"Define
P
(
D
)
{\displaystyle P(D)}
to be the differential operator given by
P
(
D
)
=
D
2
+
5
D
+
6
{\displaystyle P(D)=D^{2}+5D+6}
, where
D
{\displaystyle D}
is the differentiation operator. Then
P
(
D
)
(
sin
(
x
)
)
=
−
sin
(
x
)
+
5
cos
(
x
)
+
6
{\displaystyle P(D)(\sin(x))=-\sin(x)+5\cos(x)+6}
."