Index: src/math.c
==================================================================
--- src/math.c
+++ src/math.c
@@ -213,10 +213,17 @@
   if( r.approx==0 && A.m%B.m!=0 ) r.approx = 1;
   r.m = A.m/B.m;
   r.e = A.e - B.e;
   return r;
 }
+
+/*
+** Test if A is NaN.
+*/
+int sqlite4_num_isnan(sqlite4_num A){
+  return A.e>SQLITE4_MX_EXP && A.m==0; 
+}
 
 /*
 ** Compare numbers A and B.  Return:
 **
 **    1     if A<B