Add comment about FLT_RADIX.

diff --git a/lib/printf-frexp.c b/lib/printf-frexp.c
index 46750e485ec04bf506beb71bf39d039ace5e2491..e6032a4fb0fe9d4a61707d3c1ea5a856112f2528 100644 (file)
--- a/lib/printf-frexp.c
+++ b/lib/printf-frexp.c
@@ -29,6 +29,10 @@
 # include <float.h>
 # include <math.h>
 
+/* This file assumes FLT_RADIX = 2.  If FLT_RADIX is a power of 2 greater
+   than 2, or not even a power of 2, some rounding errors can occur, so that
+   then the returned mantissa is only guaranteed to be <= 2.0, not < 2.0.  */
+
 # ifdef USE_LONG_DOUBLE
 #  define FUNC printf_frexpl
 #  define DOUBLE long double