math/big: implement/rename accessors for precision and rounding mode

Also: remove NewFloat - not needed anymore. Work-around for places
where has been used so far:

NewFloat(x, prec, mode) === new(Float).SetMode(mode).SetPrec(prec).SetFloat64(x)

However, if mode == ToNearestEven, SetMode is not needed. SetPrec
is needed if the default precision (53 after SetFloat64) is not
adequate.

TBR adonovan

Change-Id: Ifda12c479ba157f2dea306c32b47c7afbf31e759
Reviewed-on: https://go-review.googlesource.com/4842
Reviewed-by: Robert Griesemer <gri@golang.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/math/big/floatconv.go b/src/math/big/floatconv.go
index 511cc51889..04f9a4e1b4 100644
--- a/src/math/big/floatconv.go
+++ b/src/math/big/floatconv.go
@@ -151,13 +151,13 @@ func (z *Float) Parse(s string, base int) (f *Float, b int, err error) {
 // ScanFloat is like f.Scan(r, base) with f set to the given precision
 // and rounding mode.
 func ScanFloat(r io.ByteScanner, base int, prec uint, mode RoundingMode) (f *Float, b int, err error) {
-	return NewFloat(0, prec, mode).Scan(r, base)
+	return new(Float).SetPrec(prec).SetMode(mode).Scan(r, base)
 }
 
 // ParseFloat is like f.Parse(s, base) with f set to the given precision
 // and rounding mode.
 func ParseFloat(s string, base int, prec uint, mode RoundingMode) (f *Float, b int, err error) {
-	return NewFloat(0, prec, mode).Parse(s, base)
+	return new(Float).SetPrec(prec).SetMode(mode).Parse(s, base)
 }
 
 // Format converts the floating-point number x to a string according