These functions check whether the argument x
is a single
atomic value of type numeric
, integer
or
character
.
If x
does have the required length and type, the result
of the function is the logical value TRUE
.
If x
does not have the required length and type,
then if fatal=TRUE
(the default) an error occurs,
while if fatal=FALSE
a warning is issued and the
function returns the value FALSE
.