math/big: Always print exponent sign when using 'p' exponent for Floats.

Float.Format supports the 'b' and 'p' format, both of which print
a binary ('p') exponent. The 'b' format always printed a sign ('+'
or '-') for the exponent; the 'p' format only printed a negative
sign for the exponent. This change makes the two consistent. It
also makes the 'p' format easier to read if the exponent is >= 0.

Also:
- Comments added elsewhere.

Change-Id: Ifd2e01bdafb3043345972ca22a90248d055bd29b
Reviewed-on: https://go-review.googlesource.com/10359
Reviewed-by: Alan Donovan <adonovan@google.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/math/big/float.go b/src/math/big/float.go
index dcb72c5754..e663c1c6ac 100644
--- a/src/math/big/float.go
+++ b/src/math/big/float.go
@@ -913,6 +913,7 @@ func (x *Float) Float32() (float32, Accuracy) {
 			}
 			return float32(math.Inf(+1)), Above
 		}
+		// e <= emax
 
 		// Determine sign, biased exponent, and mantissa.
 		var sign, bexp, mant uint32
@@ -1019,6 +1020,7 @@ func (x *Float) Float64() (float64, Accuracy) {
 			}
 			return math.Inf(+1), Above
 		}
+		// e <= emax
 
 		// Determine sign, biased exponent, and mantissa.
 		var sign, bexp, mant uint64