Use the \*(If string provided by mdoc(7), to represent infinity.

lib/msun/man/exp.3

@@ -217,10 +217,7 @@ They also provide accurate inverse hyperbolic functions.
 The function
 .Fn pow x 0
 returns x**0 = 1 for all x including x = 0,
-.if n \
-Infinity
-.if t \
-\(if
+\*(If
 (not found on a
 .Tn VAX ) ,
 and
@@ -265,10 +262,7 @@ x(0) = y(0) = 0, then x(z)**y(z) \(-> 1 as z \(-> 0.
 .Ed
 .It
 If 0**0 = 1, then
-.if n \
-infinity**0 = 1/0**0 = 1 too; and
-.if t \
-\(if**0 = 1/0**0 = 1 too; and
+\*(If**0 = 1/0**0 = 1 too; and
 then \*(Na**0 = 1 too because x**0 = 1 for all finite
 and infinite x, i.e., independently of x.
 .El

lib/msun/man/math.3

@@ -36,7 +36,6 @@
 .Dt MATH 3
 .Os
 .if n \{\
-.char \[if] "Infinity
 .char \[sr] "sqrt
 .\}
 .Sh NAME
@@ -186,7 +185,7 @@ Range:	Overflow threshold  = 2.0**1024 = 1.8e308
 	Underflow threshold = 0.5**1022 = 2.2e\-308
 .El
 .Bd -ragged -offset indent -compact
-Overflow goes by default to a signed \(if.
+Overflow goes by default to a signed \*(If.
 Underflow is
 .Em Gradual ,
 rounding to the nearest
@@ -204,19 +203,19 @@ sign are division by zero and
 .Fn copysign x \(+-0 .
 In particular, comparison (x > y, x \(>= y, etc.)\&
 cannot be affected by the sign of zero; but if
-finite x = y then \(if = 1/(x\-y) \(!= \-1/(y\-x) = \-\(if.
+finite x = y then \*(If = 1/(x\-y) \(!= \-1/(y\-x) = \-\*(If.
 .Ed
 .Pp
-\(if is signed.
+\*(If is signed.
 .Bd -ragged -offset indent -compact
 It persists when added to itself
 or to any finite number.
 Its sign transforms
 correctly through multiplication and division, and
-(finite)/\(+-\(if\0=\0\(+-0
-(nonzero)/0 = \(+-\(if.
+(finite)/\(+-\*(If\0=\0\(+-0
+(nonzero)/0 = \(+-\*(If.
 But
-\(if\-\(if, \(if\(**0 and \(if/\(if
+\*(If\-\*(If, \*(If\(**0 and \*(If/\*(If
 are, like 0/0 and sqrt(\-3),
 invalid operations that produce \*(Na. ...
 .Ed
@@ -262,7 +261,7 @@ Only rounding like IEEE 754 can do that.
 But no single kind of rounding can be
 proved best for every circumstance, so IEEE 754
 provides rounding towards zero or towards
-+\(if or towards \-\(if
++\*(If or towards \-\*(If
 at the programmer's option.
 And the
 same kinds of rounding are specified for
@@ -277,8 +276,8 @@ listed below in declining order of probable importance.
 .Bl -column -offset indent "Invalid Operation" "Gradual Underflow"
 .Em "Exception	Default Result"
 Invalid Operation	\*(Na, or FALSE
-Overflow	\(+-\(if
-Divide by Zero	\(+-\(if
+Overflow	\(+-\*(If
+Divide by Zero	\(+-\*(If
 Underflow	Gradual Underflow
 Inexact	Rounded value
 .El