add dec package as new dep

Godeps/Godeps.json

@@ -203,6 +203,10 @@
 		{
 			"ImportPath": "gopkg.in/v2/yaml",
 			"Rev": "d466437aa4adc35830964cffc5b5f262c63ddcb4"
+		},
+		{
+			"ImportPath": "speter.net/go/exp/math/dec/inf",
+			"Rev": "42ca6cd68aa922bc3f32f1e056e61b65945d9ad7"
 		}
 	]
 }

Godeps/_workspace/src/speter.net/go/exp/math/dec/inf/LICENSE

+Copyright (c) 2012 Péter Surányi. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----------------------------------------------------------------------
+Portions of inf.Dec's source code have been derived from Go and are
+covered by the following license:
+----------------------------------------------------------------------
+
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Godeps/_workspace/src/speter.net/go/exp/math/dec/inf/benchmark_test.go

+package inf
+
+import (
+	"fmt"
+	"math/big"
+	"math/rand"
+	"sync"
+	"testing"
+)
+
+const maxcap = 1024 * 1024
+const bits = 256
+const maxscale = 32
+
+var once sync.Once
+
+var decInput [][2]Dec
+var intInput [][2]big.Int
+
+var initBench = func() {
+	decInput = make([][2]Dec, maxcap)
+	intInput = make([][2]big.Int, maxcap)
+	max := new(big.Int).Lsh(big.NewInt(1), bits)
+	r := rand.New(rand.NewSource(0))
+	for i := 0; i < cap(decInput); i++ {
+		decInput[i][0].SetUnscaledBig(new(big.Int).Rand(r, max)).
+			SetScale(Scale(r.Int31n(int32(2*maxscale-1)) - int32(maxscale)))
+		decInput[i][1].SetUnscaledBig(new(big.Int).Rand(r, max)).
+			SetScale(Scale(r.Int31n(int32(2*maxscale-1)) - int32(maxscale)))
+	}
+	for i := 0; i < cap(intInput); i++ {
+		intInput[i][0].Rand(r, max)
+		intInput[i][1].Rand(r, max)
+	}
+}
+
+func doBenchmarkDec1(b *testing.B, f func(z *Dec)) {
+	once.Do(initBench)
+	b.ResetTimer()
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		f(&decInput[i%maxcap][0])
+	}
+}
+
+func doBenchmarkDec2(b *testing.B, f func(x, y *Dec)) {
+	once.Do(initBench)
+	b.ResetTimer()
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		f(&decInput[i%maxcap][0], &decInput[i%maxcap][1])
+	}
+}
+
+func doBenchmarkInt1(b *testing.B, f func(z *big.Int)) {
+	once.Do(initBench)
+	b.ResetTimer()
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		f(&intInput[i%maxcap][0])
+	}
+}
+
+func doBenchmarkInt2(b *testing.B, f func(x, y *big.Int)) {
+	once.Do(initBench)
+	b.ResetTimer()
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		f(&intInput[i%maxcap][0], &intInput[i%maxcap][1])
+	}
+}
+
+func Benchmark_Dec_String(b *testing.B) {
+	doBenchmarkDec1(b, func(x *Dec) {
+		x.String()
+	})
+}
+
+func Benchmark_Dec_StringScan(b *testing.B) {
+	doBenchmarkDec1(b, func(x *Dec) {
+		s := x.String()
+		d := new(Dec)
+		fmt.Sscan(s, d)
+	})
+}
+
+func Benchmark_Dec_GobEncode(b *testing.B) {
+	doBenchmarkDec1(b, func(x *Dec) {
+		x.GobEncode()
+	})
+}
+
+func Benchmark_Dec_GobEnDecode(b *testing.B) {
+	doBenchmarkDec1(b, func(x *Dec) {
+		g, _ := x.GobEncode()
+		new(Dec).GobDecode(g)
+	})
+}
+
+func Benchmark_Dec_Add(b *testing.B) {
+	doBenchmarkDec2(b, func(x, y *Dec) {
+		ys := y.Scale()
+		y.SetScale(x.Scale())
+		_ = new(Dec).Add(x, y)
+		y.SetScale(ys)
+	})
+}
+
+func Benchmark_Dec_AddMixed(b *testing.B) {
+	doBenchmarkDec2(b, func(x, y *Dec) {
+		_ = new(Dec).Add(x, y)
+	})
+}
+
+func Benchmark_Dec_Sub(b *testing.B) {
+	doBenchmarkDec2(b, func(x, y *Dec) {
+		ys := y.Scale()
+		y.SetScale(x.Scale())
+		_ = new(Dec).Sub(x, y)
+		y.SetScale(ys)
+	})
+}
+
+func Benchmark_Dec_SubMixed(b *testing.B) {
+	doBenchmarkDec2(b, func(x, y *Dec) {
+		_ = new(Dec).Sub(x, y)
+	})
+}
+
+func Benchmark_Dec_Mul(b *testing.B) {
+	doBenchmarkDec2(b, func(x, y *Dec) {
+		_ = new(Dec).Mul(x, y)
+	})
+}
+
+func Benchmark_Dec_Mul_QuoExact(b *testing.B) {
+	doBenchmarkDec2(b, func(x, y *Dec) {
+		v := new(Dec).Mul(x, y)
+		_ = new(Dec).QuoExact(v, y)
+	})
+}
+
+func Benchmark_Dec_QuoRound_Fixed_Down(b *testing.B) {
+	doBenchmarkDec2(b, func(x, y *Dec) {
+		_ = new(Dec).QuoRound(x, y, 0, RoundDown)
+	})
+}
+
+func Benchmark_Dec_QuoRound_Fixed_HalfUp(b *testing.B) {
+	doBenchmarkDec2(b, func(x, y *Dec) {
+		_ = new(Dec).QuoRound(x, y, 0, RoundHalfUp)
+	})
+}
+
+func Benchmark_Int_String(b *testing.B) {
+	doBenchmarkInt1(b, func(x *big.Int) {
+		x.String()
+	})
+}
+
+func Benchmark_Int_StringScan(b *testing.B) {
+	doBenchmarkInt1(b, func(x *big.Int) {
+		s := x.String()
+		d := new(big.Int)
+		fmt.Sscan(s, d)
+	})
+}
+
+func Benchmark_Int_GobEncode(b *testing.B) {
+	doBenchmarkInt1(b, func(x *big.Int) {
+		x.GobEncode()
+	})
+}
+
+func Benchmark_Int_GobEnDecode(b *testing.B) {
+	doBenchmarkInt1(b, func(x *big.Int) {
+		g, _ := x.GobEncode()
+		new(big.Int).GobDecode(g)
+	})
+}
+
+func Benchmark_Int_Add(b *testing.B) {
+	doBenchmarkInt2(b, func(x, y *big.Int) {
+		_ = new(big.Int).Add(x, y)
+	})
+}
+
+func Benchmark_Int_Sub(b *testing.B) {
+	doBenchmarkInt2(b, func(x, y *big.Int) {
+		_ = new(big.Int).Sub(x, y)
+	})
+}
+
+func Benchmark_Int_Mul(b *testing.B) {
+	doBenchmarkInt2(b, func(x, y *big.Int) {
+		_ = new(big.Int).Mul(x, y)
+	})
+}
+
+func Benchmark_Int_Quo(b *testing.B) {
+	doBenchmarkInt2(b, func(x, y *big.Int) {
+		_ = new(big.Int).Quo(x, y)
+	})
+}
+
+func Benchmark_Int_QuoRem(b *testing.B) {
+	doBenchmarkInt2(b, func(x, y *big.Int) {
+		_, _ = new(big.Int).QuoRem(x, y, new(big.Int))
+	})
+}

Godeps/_workspace/src/speter.net/go/exp/math/dec/inf/dec_go1_2_test.go

+// +build go1.2
+
+package inf
+
+import (
+	"encoding"
+	"encoding/json"
+	"testing"
+)
+
+var _ encoding.TextMarshaler = new(Dec)
+var _ encoding.TextUnmarshaler = new(Dec)
+
+type Obj struct {
+	Val *Dec
+}
+
+func TestDecJsonMarshalUnmarshal(t *testing.T) {
+	o := Obj{Val: NewDec(123, 2)}
+	js, err := json.Marshal(o)
+	if err != nil {
+		t.Fatalf("json.Marshal(%v): got %v, want ok", o, err)
+	}
+	o2 := &Obj{}
+	err = json.Unmarshal(js, o2)
+	if err != nil {
+		t.Fatalf("json.Unmarshal(%#q): got %v, want ok", js, err)
+	}
+	if o.Val.Scale() != o2.Val.Scale() ||
+		o.Val.UnscaledBig().Cmp(o2.Val.UnscaledBig()) != 0 {
+		t.Fatalf("json.Unmarshal(json.Marshal(%v)): want %v, got %v", o, o, o2)
+	}
+}

Godeps/_workspace/src/speter.net/go/exp/math/dec/inf/dec_internal_test.go

+package inf
+
+import (
+	"math/big"
+	"testing"
+)
+
+var decQuoRemZZZ = []struct {
+	z, x, y  *Dec
+	r        *big.Rat
+	srA, srB int
+}{
+	// basic examples
+	{NewDec(1, 0), NewDec(2, 0), NewDec(2, 0), big.NewRat(0, 1), 0, 1},
+	{NewDec(15, 1), NewDec(3, 0), NewDec(2, 0), big.NewRat(0, 1), 0, 1},
+	{NewDec(1, 1), NewDec(1, 0), NewDec(10, 0), big.NewRat(0, 1), 0, 1},
+	{NewDec(0, 0), NewDec(2, 0), NewDec(3, 0), big.NewRat(2, 3), 1, 1},
+	{NewDec(0, 0), NewDec(2, 0), NewDec(6, 0), big.NewRat(1, 3), 1, 1},
+	{NewDec(1, 1), NewDec(2, 0), NewDec(12, 0), big.NewRat(2, 3), 1, 1},
+
+	// examples from the Go Language Specification
+	{NewDec(1, 0), NewDec(5, 0), NewDec(3, 0), big.NewRat(2, 3), 1, 1},
+	{NewDec(-1, 0), NewDec(-5, 0), NewDec(3, 0), big.NewRat(-2, 3), -1, 1},
+	{NewDec(-1, 0), NewDec(5, 0), NewDec(-3, 0), big.NewRat(-2, 3), 1, -1},
+	{NewDec(1, 0), NewDec(-5, 0), NewDec(-3, 0), big.NewRat(2, 3), -1, -1},
+}
+
+func TestDecQuoRem(t *testing.T) {
+	for i, a := range decQuoRemZZZ {
+		z, rA, rB := new(Dec), new(big.Int), new(big.Int)
+		s := scaleQuoExact{}.Scale(a.x, a.y)
+		z.quoRem(a.x, a.y, s, true, rA, rB)
+		if a.z.Cmp(z) != 0 || a.r.Cmp(new(big.Rat).SetFrac(rA, rB)) != 0 {
+			t.Errorf("#%d QuoRemZZZ got %v, %v, %v; expected %v, %v", i, z, rA, rB, a.z, a.r)
+		}
+		if a.srA != rA.Sign() || a.srB != rB.Sign() {
+			t.Errorf("#%d QuoRemZZZ wrong signs, got %v, %v; expected %v, %v", i, rA.Sign(), rB.Sign(), a.srA, a.srB)
+		}
+	}
+}

Godeps/_workspace/src/speter.net/go/exp/math/dec/inf/example_test.go

+package inf_test
+
+import (
+	"fmt"
+	"log"
+)
+
+import "speter.net/go/exp/math/dec/inf"
+
+func ExampleDec_SetString() {
+	d := new(inf.Dec)
+	d.SetString("012345.67890") // decimal; leading 0 ignored; trailing 0 kept
+	fmt.Println(d)
+	// Output: 12345.67890
+}
+
+func ExampleDec_Scan() {
+	// The Scan function is rarely used directly;
+	// the fmt package recognizes it as an implementation of fmt.Scanner.
+	d := new(inf.Dec)
+	_, err := fmt.Sscan("184467440.73709551617", d)
+	if err != nil {
+		log.Println("error scanning value:", err)
+	} else {
+		fmt.Println(d)
+	}
+	// Output: 184467440.73709551617
+}
+
+func ExampleDec_QuoRound_scale2RoundDown() {
+	// 10 / 3 is an infinite decimal; it has no exact Dec representation
+	x, y := inf.NewDec(10, 0), inf.NewDec(3, 0)
+	// use 2 digits beyond the decimal point, round towards 0
+	z := new(inf.Dec).QuoRound(x, y, 2, inf.RoundDown)
+	fmt.Println(z)
+	// Output: 3.33
+}
+
+func ExampleDec_QuoRound_scale2RoundCeil() {
+	// -42 / 400 is an finite decimal with 3 digits beyond the decimal point
+	x, y := inf.NewDec(-42, 0), inf.NewDec(400, 0)
+	// use 2 digits beyond decimal point, round towards positive infinity
+	z := new(inf.Dec).QuoRound(x, y, 2, inf.RoundCeil)
+	fmt.Println(z)
+	// Output: -0.10
+}
+
+func ExampleDec_QuoExact_ok() {
+	// 1 / 25 is a finite decimal; it has exact Dec representation
+	x, y := inf.NewDec(1, 0), inf.NewDec(25, 0)
+	z := new(inf.Dec).QuoExact(x, y)
+	fmt.Println(z)
+	// Output: 0.04
+}
+
+func ExampleDec_QuoExact_fail() {
+	// 1 / 3 is an infinite decimal; it has no exact Dec representation
+	x, y := inf.NewDec(1, 0), inf.NewDec(3, 0)
+	z := new(inf.Dec).QuoExact(x, y)
+	fmt.Println(z)
+	// Output: <nil>
+}

Godeps/_workspace/src/speter.net/go/exp/math/dec/inf/rounder.go

+package inf
+
+import (
+	"math/big"
+)
+
+// Rounder represents a method for rounding the (possibly infinite decimal)
+// result of a division to a finite Dec. It is used by Dec.Round() and
+// Dec.Quo().
+//
+// See the Example for results of using each Rounder with some sample values.
+//
+type Rounder rounder
+
+// See http://speleotrove.com/decimal/damodel.html#refround for more detailed
+// definitions of these rounding modes.
+var (
+	RoundDown     Rounder // towards 0
+	RoundUp       Rounder // away from 0
+	RoundFloor    Rounder // towards -infinity
+	RoundCeil     Rounder // towards +infinity
+	RoundHalfDown Rounder // to nearest; towards 0 if same distance
+	RoundHalfUp   Rounder // to nearest; away from 0 if same distance
+	RoundHalfEven Rounder // to nearest; even last digit if same distance
+)
+
+// RoundExact is to be used in the case when rounding is not necessary.
+// When used with Quo or Round, it returns the result verbatim when it can be
+// expressed exactly with the given precision, and it returns nil otherwise.
+// QuoExact is a shorthand for using Quo with RoundExact.
+var RoundExact Rounder
+
+type rounder interface {
+
+	// When UseRemainder() returns true, the Round() method is passed the
+	// remainder of the division, expressed as the numerator and denominator of
+	// a rational.
+	UseRemainder() bool
+
+	// Round sets the rounded value of a quotient to z, and returns z.
+	// quo is rounded down (truncated towards zero) to the scale obtained from
+	// the Scaler in Quo().
+	//
+	// When the remainder is not used, remNum and remDen are nil.
+	// When used, the remainder is normalized between -1 and 1; that is:
+	//
+	//  -|remDen| < remNum < |remDen|
+	//
+	// remDen has the same sign as y, and remNum is zero or has the same sign
+	// as x.
+	Round(z, quo *Dec, remNum, remDen *big.Int) *Dec
+}
+
+type rndr struct {
+	useRem bool
+	round  func(z, quo *Dec, remNum, remDen *big.Int) *Dec
+}
+
+func (r rndr) UseRemainder() bool {
+	return r.useRem
+}
+
+func (r rndr) Round(z, quo *Dec, remNum, remDen *big.Int) *Dec {
+	return r.round(z, quo, remNum, remDen)
+}
+
+var intSign = []*big.Int{big.NewInt(-1), big.NewInt(0), big.NewInt(1)}
+
+func roundHalf(f func(c int, odd uint) (roundUp bool)) func(z, q *Dec, rA, rB *big.Int) *Dec {
+	return func(z, q *Dec, rA, rB *big.Int) *Dec {
+		z.Set(q)
+		brA, brB := rA.BitLen(), rB.BitLen()
+		if brA < brB-1 {
+			// brA < brB-1 => |rA| < |rB/2|
+			return z
+		}
+		roundUp := false
+		srA, srB := rA.Sign(), rB.Sign()
+		s := srA * srB
+		if brA == brB-1 {
+			rA2 := new(big.Int).Lsh(rA, 1)
+			if s < 0 {
+				rA2.Neg(rA2)
+			}
+			roundUp = f(rA2.Cmp(rB)*srB, z.UnscaledBig().Bit(0))
+		} else {
+			// brA > brB-1 => |rA| > |rB/2|
+			roundUp = true
+		}
+		if roundUp {
+			z.UnscaledBig().Add(z.UnscaledBig(), intSign[s+1])
+		}
+		return z
+	}
+}
+
+func init() {
+	RoundExact = rndr{true,
+		func(z, q *Dec, rA, rB *big.Int) *Dec {
+			if rA.Sign() != 0 {
+				return nil
+			}
+			return z.Set(q)
+		}}
+	RoundDown = rndr{false,
+		func(z, q *Dec, rA, rB *big.Int) *Dec {
+			return z.Set(q)
+		}}
+	RoundUp = rndr{true,
+		func(z, q *Dec, rA, rB *big.Int) *Dec {
+			z.Set(q)
+			if rA.Sign() != 0 {
+				z.UnscaledBig().Add(z.UnscaledBig(), intSign[rA.Sign()*rB.Sign()+1])
+			}
+			return z
+		}}
+	RoundFloor = rndr{true,
+		func(z, q *Dec, rA, rB *big.Int) *Dec {
+			z.Set(q)
+			if rA.Sign()*rB.Sign() < 0 {
+				z.UnscaledBig().Add(z.UnscaledBig(), intSign[0])
+			}
+			return z
+		}}
+	RoundCeil = rndr{true,
+		func(z, q *Dec, rA, rB *big.Int) *Dec {
+			z.Set(q)
+			if rA.Sign()*rB.Sign() > 0 {
+				z.UnscaledBig().Add(z.UnscaledBig(), intSign[2])
+			}
+			return z
+		}}
+	RoundHalfDown = rndr{true, roundHalf(
+		func(c int, odd uint) bool {
+			return c > 0
+		})}
+	RoundHalfUp = rndr{true, roundHalf(
+		func(c int, odd uint) bool {
+			return c >= 0
+		})}
+	RoundHalfEven = rndr{true, roundHalf(
+		func(c int, odd uint) bool {
+			return c > 0 || c == 0 && odd == 1
+		})}
+}

Godeps/_workspace/src/speter.net/go/exp/math/dec/inf/rounder_example_test.go

+package inf_test
+
+import (
+	"fmt"
+	"os"
+	"text/tabwriter"
+
+	"speter.net/go/exp/math/dec/inf"
+)
+
+// This example displays the results of Dec.Round with each of the Rounders.
+//
+func ExampleRounder() {
+	var vals = []struct {
+		x string
+		s inf.Scale
+	}{
+		{"-0.18", 1}, {"-0.15", 1}, {"-0.12", 1}, {"-0.10", 1},
+		{"-0.08", 1}, {"-0.05", 1}, {"-0.02", 1}, {"0.00", 1},
+		{"0.02", 1}, {"0.05", 1}, {"0.08", 1}, {"0.10", 1},
+		{"0.12", 1}, {"0.15", 1}, {"0.18", 1},
+	}
+
+	var rounders = []struct {
+		name    string
+		rounder inf.Rounder
+	}{
+		{"RoundDown", inf.RoundDown}, {"RoundUp", inf.RoundUp},
+		{"RoundCeil", inf.RoundCeil}, {"RoundFloor", inf.RoundFloor},
+		{"RoundHalfDown", inf.RoundHalfDown}, {"RoundHalfUp", inf.RoundHalfUp},
+		{"RoundHalfEven", inf.RoundHalfEven}, {"RoundExact", inf.RoundExact},
+	}
+
+	fmt.Println("The results of new(inf.Dec).Round(x, s, inf.RoundXXX):\n")
+	w := tabwriter.NewWriter(os.Stdout, 0, 0, 1, ' ', tabwriter.AlignRight)
+	fmt.Fprint(w, "x\ts\t|\t")
+	for _, r := range rounders {
+		fmt.Fprintf(w, "%s\t", r.name[5:])
+	}
+	fmt.Fprintln(w)
+	for _, v := range vals {
+		fmt.Fprintf(w, "%s\t%d\t|\t", v.x, v.s)
+		for _, r := range rounders {
+			x, _ := new(inf.Dec).SetString(v.x)
+			z := new(inf.Dec).Round(x, v.s, r.rounder)
+			fmt.Fprintf(w, "%d\t", z)
+		}
+		fmt.Fprintln(w)
+	}
+	w.Flush()
+
+	// Output:
+	// The results of new(inf.Dec).Round(x, s, inf.RoundXXX):
+	//
+	//      x s | Down   Up Ceil Floor HalfDown HalfUp HalfEven Exact
+	//  -0.18 1 | -0.1 -0.2 -0.1  -0.2     -0.2   -0.2     -0.2 <nil>
+	//  -0.15 1 | -0.1 -0.2 -0.1  -0.2     -0.1   -0.2     -0.2 <nil>
+	//  -0.12 1 | -0.1 -0.2 -0.1  -0.2     -0.1   -0.1     -0.1 <nil>
+	//  -0.10 1 | -0.1 -0.1 -0.1  -0.1     -0.1   -0.1     -0.1  -0.1
+	//  -0.08 1 |  0.0 -0.1  0.0  -0.1     -0.1   -0.1     -0.1 <nil>
+	//  -0.05 1 |  0.0 -0.1  0.0  -0.1      0.0   -0.1      0.0 <nil>
+	//  -0.02 1 |  0.0 -0.1  0.0  -0.1      0.0    0.0      0.0 <nil>
+	//   0.00 1 |  0.0  0.0  0.0   0.0      0.0    0.0      0.0   0.0
+	//   0.02 1 |  0.0  0.1  0.1   0.0      0.0    0.0      0.0 <nil>
+	//   0.05 1 |  0.0  0.1  0.1   0.0      0.0    0.1      0.0 <nil>
+	//   0.08 1 |  0.0  0.1  0.1   0.0      0.1    0.1      0.1 <nil>
+	//   0.10 1 |  0.1  0.1  0.1   0.1      0.1    0.1      0.1   0.1
+	//   0.12 1 |  0.1  0.2  0.2   0.1      0.1    0.1      0.1 <nil>
+	//   0.15 1 |  0.1  0.2  0.2   0.1      0.1    0.2      0.2 <nil>
+	//   0.18 1 |  0.1  0.2  0.2   0.1      0.2    0.2      0.2 <nil>
+
+}

Godeps/_workspace/src/speter.net/go/exp/math/dec/inf/rounder_test.go

+package inf_test
+
+import (
+	"math/big"
+	"testing"
+
+	"speter.net/go/exp/math/dec/inf"
+)
+
+var decRounderInputs = [...]struct {
+	quo    *inf.Dec
+	rA, rB *big.Int
+}{
+	// examples from go language spec
+	{inf.NewDec(1, 0), big.NewInt(2), big.NewInt(3)},   //  5 /  3
+	{inf.NewDec(-1, 0), big.NewInt(-2), big.NewInt(3)}, // -5 /  3
+	{inf.NewDec(-1, 0), big.NewInt(2), big.NewInt(-3)}, //  5 / -3
+	{inf.NewDec(1, 0), big.NewInt(-2), big.NewInt(-3)}, // -5 / -3
+	// examples from godoc
+	{inf.NewDec(-1, 1), big.NewInt(-8), big.NewInt(10)},
+	{inf.NewDec(-1, 1), big.NewInt(-5), big.NewInt(10)},
+	{inf.NewDec(-1, 1), big.NewInt(-2), big.NewInt(10)},
+	{inf.NewDec(0, 1), big.NewInt(-8), big.NewInt(10)},
+	{inf.NewDec(0, 1), big.NewInt(-5), big.NewInt(10)},
+	{inf.NewDec(0, 1), big.NewInt(-2), big.NewInt(10)},
+	{inf.NewDec(0, 1), big.NewInt(0), big.NewInt(1)},
+	{inf.NewDec(0, 1), big.NewInt(2), big.NewInt(10)},
+	{inf.NewDec(0, 1), big.NewInt(5), big.NewInt(10)},
+	{inf.NewDec(0, 1), big.NewInt(8), big.NewInt(10)},
+	{inf.NewDec(1, 1), big.NewInt(2), big.NewInt(10)},
+	{inf.NewDec(1, 1), big.NewInt(5), big.NewInt(10)},
+	{inf.NewDec(1, 1), big.NewInt(8), big.NewInt(10)},
+}
+
+var decRounderResults = [...]struct {
+	rounder inf.Rounder
+	results [len(decRounderInputs)]*inf.Dec
+}{
+	{inf.RoundExact, [...]*inf.Dec{nil, nil, nil, nil,
+		nil, nil, nil, nil, nil, nil,
+		inf.NewDec(0, 1), nil, nil, nil, nil, nil, nil}},
+	{inf.RoundDown, [...]*inf.Dec{
+		inf.NewDec(1, 0), inf.NewDec(-1, 0), inf.NewDec(-1, 0), inf.NewDec(1, 0),
+		inf.NewDec(-1, 1), inf.NewDec(-1, 1), inf.NewDec(-1, 1),
+		inf.NewDec(0, 1), inf.NewDec(0, 1), inf.NewDec(0, 1),
+		inf.NewDec(0, 1),
+		inf.NewDec(0, 1), inf.NewDec(0, 1), inf.NewDec(0, 1),
+		inf.NewDec(1, 1), inf.NewDec(1, 1), inf.NewDec(1, 1)}},
+	{inf.RoundUp, [...]*inf.Dec{
+		inf.NewDec(2, 0), inf.NewDec(-2, 0), inf.NewDec(-2, 0), inf.NewDec(2, 0),
+		inf.NewDec(-2, 1), inf.NewDec(-2, 1), inf.NewDec(-2, 1),
+		inf.NewDec(-1, 1), inf.NewDec(-1, 1), inf.NewDec(-1, 1),
+		inf.NewDec(0, 1),
+		inf.NewDec(1, 1), inf.NewDec(1, 1), inf.NewDec(1, 1),
+		inf.NewDec(2, 1), inf.NewDec(2, 1), inf.NewDec(2, 1)}},
+	{inf.RoundHalfDown, [...]*inf.Dec{
+		inf.NewDec(2, 0), inf.NewDec(-2, 0), inf.NewDec(-2, 0), inf.NewDec(2, 0),
+		inf.NewDec(-2, 1), inf.NewDec(-1, 1), inf.NewDec(-1, 1),
+		inf.NewDec(-1, 1), inf.NewDec(0, 1), inf.NewDec(0, 1),
+		inf.NewDec(0, 1),
+		inf.NewDec(0, 1), inf.NewDec(0, 1), inf.NewDec(1, 1),
+		inf.NewDec(1, 1), inf.NewDec(1, 1), inf.NewDec(2, 1)}},
+	{inf.RoundHalfUp, [...]*inf.Dec{
+		inf.NewDec(2, 0), inf.NewDec(-2, 0), inf.NewDec(-2, 0), inf.NewDec(2, 0),
+		inf.NewDec(-2, 1), inf.NewDec(-2, 1), inf.NewDec(-1, 1),
+		inf.NewDec(-1, 1), inf.NewDec(-1, 1), inf.NewDec(0, 1),
+		inf.NewDec(0, 1),
+		inf.NewDec(0, 1), inf.NewDec(1, 1), inf.NewDec(1, 1),
+		inf.NewDec(1, 1), inf.NewDec(2, 1), inf.NewDec(2, 1)}},
+	{inf.RoundHalfEven, [...]*inf.Dec{
+		inf.NewDec(2, 0), inf.NewDec(-2, 0), inf.NewDec(-2, 0), inf.NewDec(2, 0),
+		inf.NewDec(-2, 1), inf.NewDec(-2, 1), inf.NewDec(-1, 1),
+		inf.NewDec(-1, 1), inf.NewDec(0, 1), inf.NewDec(0, 1),
+		inf.NewDec(0, 1),
+		inf.NewDec(0, 1), inf.NewDec(0, 1), inf.NewDec(1, 1),
+		inf.NewDec(1, 1), inf.NewDec(2, 1), inf.NewDec(2, 1)}},
+	{inf.RoundFloor, [...]*inf.Dec{
+		inf.NewDec(1, 0), inf.NewDec(-2, 0), inf.NewDec(-2, 0), inf.NewDec(1, 0),
+		inf.NewDec(-2, 1), inf.NewDec(-2, 1), inf.NewDec(-2, 1),
+		inf.NewDec(-1, 1), inf.NewDec(-1, 1), inf.NewDec(-1, 1),
+		inf.NewDec(0, 1),
+		inf.NewDec(0, 1), inf.NewDec(0, 1), inf.NewDec(0, 1),
+		inf.NewDec(1, 1), inf.NewDec(1, 1), inf.NewDec(1, 1)}},
+	{inf.RoundCeil, [...]*inf.Dec{
+		inf.NewDec(2, 0), inf.NewDec(-1, 0), inf.NewDec(-1, 0), inf.NewDec(2, 0),
+		inf.NewDec(-1, 1), inf.NewDec(-1, 1), inf.NewDec(-1, 1),
+		inf.NewDec(0, 1), inf.NewDec(0, 1), inf.NewDec(0, 1),
+		inf.NewDec(0, 1),
+		inf.NewDec(1, 1), inf.NewDec(1, 1), inf.NewDec(1, 1),
+		inf.NewDec(2, 1), inf.NewDec(2, 1), inf.NewDec(2, 1)}},
+}
+
+func TestDecRounders(t *testing.T) {
+	for i, a := range decRounderResults {
+		for j, input := range decRounderInputs {
+			q := new(inf.Dec).Set(input.quo)
+			rA, rB := new(big.Int).Set(input.rA), new(big.Int).Set(input.rB)
+			res := a.rounder.Round(new(inf.Dec), q, rA, rB)
+			if a.results[j] == nil && res == nil {
+				continue
+			}
+			if (a.results[j] == nil && res != nil) ||
+				(a.results[j] != nil && res == nil) ||
+				a.results[j].Cmp(res) != 0 {
+				t.Errorf("#%d,%d Rounder got %v; expected %v", i, j, res, a.results[j])
+			}
+		}
+	}
+}