.BG
.FN Logic
.FN &
.FN |
.FN !
.FN xor
.TL
Logical Operators
.CS
e1 & e2
e1 | e2
! e1
xor(e1, e2)
.PP
.AG e1,e2
logical vectors.  Missing values (`NA's) are allowed.
.RT
logical result of and-ing, or-ing, negation or exclusive or-ing.
For all but negation, the result is as long as the longer of the operands.
Corresponding to
.Co NA s
in the operands will be either a logical value or an `NA', depending on
whether the other operand uniquely determines the answer; for example,
`NA\^|\^TRUE' must be `TRUE', and `NA\^&\^FALSE' must be `FALSE'.
.PP
See section 5.1.5 for the rules for dealing with operands with attributes.
.SA
`if' for the `||' and `&&' operators:
sequential evaluation of expressions.
.EX
x[a>13 & b<2]     #elements of x corresp. to a>13 and b<2

a <- c(T,F,NA)
outer(a,a,"&")  # logic table for &
.KW logic
.WR
