diff --git a/common.scad b/common.scad
index 2761025..a888cc8 100644
--- a/common.scad
+++ b/common.scad
@@ -73,6 +73,18 @@ function is_int(n) = is_num(n) && n == round(n);
 function is_integer(n) = is_num(n) && n == round(n);
 
 
+// Function: is_nan()
+// Usage:
+//   is_nan(x);
+// Description:
+//   Returns true if a given value `x` is nan, a floating point value representing "not a number".
+//   This test is far more complicated than it should be, because while arguable correct, the tests
+//   `is_num(nan)` and `nan==nan` both returns false.
+function is_nan(x) =
+	!is_num(x) && !is_undef(x) && !is_string(x) &&
+	!is_list(x) && !(x<=INF) && is_undef(x[0]);
+
+
 
 // Section: Handling `undef`s.
 
diff --git a/math.scad b/math.scad
index ab977a6..f6b4c2d 100644
--- a/math.scad
+++ b/math.scad
@@ -14,6 +14,10 @@ PHI = (1+sqrt(5))/2;  // The golden ratio phi.
 
 EPSILON = 1e-9;  // A really small value useful in comparing FP numbers.  ie: abs(a-b)<EPSILON
 
+INF = 1/0;  // The value `inf`, useful for comparisons.
+
+NAN = acos(2);  // The value `nan`, useful for comparisons.
+
 
 
 // Section: Simple math
diff --git a/version.scad b/version.scad
index 8de1cb2..e67f65e 100644
--- a/version.scad
+++ b/version.scad
@@ -8,7 +8,7 @@
 //////////////////////////////////////////////////////////////////////
 
 
-BOSL_VERSION = [2,0,116];
+BOSL_VERSION = [2,0,117];
 
 
 // Section: BOSL Library Version Functions