c2047754c3
Compiler changes:
* Change map assignment to use mapassign and assign value directly.
* Change string iteration to use decoderune, faster for ASCII strings.
* Change makeslice to take int, and use makeslice64 for larger values.
* Add new noverflow field to hmap struct used for maps.
Unresolved problems, to be fixed later:
* Commented out test in go/types/sizes_test.go that doesn't compile.
* Commented out reflect.TestStructOf test for padding after zero-sized field.
Reviewed-on: https://go-review.googlesource.com/35231
gotools/:
Updates for Go 1.8rc1.
* Makefile.am (go_cmd_go_files): Add bug.go.
(s-zdefaultcc): Write defaultPkgConfig.
* Makefile.in: Rebuild.
From-SVN: r244456
144 lines
3.6 KiB
Go
144 lines
3.6 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// +build ignore
|
|
|
|
package big_test
|
|
|
|
import (
|
|
"fmt"
|
|
"math"
|
|
"math/big"
|
|
)
|
|
|
|
func ExampleFloat_Add() {
|
|
// Operate on numbers of different precision.
|
|
var x, y, z big.Float
|
|
x.SetInt64(1000) // x is automatically set to 64bit precision
|
|
y.SetFloat64(2.718281828) // y is automatically set to 53bit precision
|
|
z.SetPrec(32)
|
|
z.Add(&x, &y)
|
|
fmt.Printf("x = %.10g (%s, prec = %d, acc = %s)\n", &x, x.Text('p', 0), x.Prec(), x.Acc())
|
|
fmt.Printf("y = %.10g (%s, prec = %d, acc = %s)\n", &y, y.Text('p', 0), y.Prec(), y.Acc())
|
|
fmt.Printf("z = %.10g (%s, prec = %d, acc = %s)\n", &z, z.Text('p', 0), z.Prec(), z.Acc())
|
|
// Output:
|
|
// x = 1000 (0x.fap+10, prec = 64, acc = Exact)
|
|
// y = 2.718281828 (0x.adf85458248cd8p+2, prec = 53, acc = Exact)
|
|
// z = 1002.718282 (0x.faadf854p+10, prec = 32, acc = Below)
|
|
}
|
|
|
|
func ExampleFloat_shift() {
|
|
// Implement Float "shift" by modifying the (binary) exponents directly.
|
|
for s := -5; s <= 5; s++ {
|
|
x := big.NewFloat(0.5)
|
|
x.SetMantExp(x, x.MantExp(nil)+s) // shift x by s
|
|
fmt.Println(x)
|
|
}
|
|
// Output:
|
|
// 0.015625
|
|
// 0.03125
|
|
// 0.0625
|
|
// 0.125
|
|
// 0.25
|
|
// 0.5
|
|
// 1
|
|
// 2
|
|
// 4
|
|
// 8
|
|
// 16
|
|
}
|
|
|
|
func ExampleFloat_Cmp() {
|
|
inf := math.Inf(1)
|
|
zero := 0.0
|
|
|
|
operands := []float64{-inf, -1.2, -zero, 0, +1.2, +inf}
|
|
|
|
fmt.Println(" x y cmp")
|
|
fmt.Println("---------------")
|
|
for _, x64 := range operands {
|
|
x := big.NewFloat(x64)
|
|
for _, y64 := range operands {
|
|
y := big.NewFloat(y64)
|
|
fmt.Printf("%4g %4g %3d\n", x, y, x.Cmp(y))
|
|
}
|
|
fmt.Println()
|
|
}
|
|
|
|
// Output:
|
|
// x y cmp
|
|
// ---------------
|
|
// -Inf -Inf 0
|
|
// -Inf -1.2 -1
|
|
// -Inf -0 -1
|
|
// -Inf 0 -1
|
|
// -Inf 1.2 -1
|
|
// -Inf +Inf -1
|
|
//
|
|
// -1.2 -Inf 1
|
|
// -1.2 -1.2 0
|
|
// -1.2 -0 -1
|
|
// -1.2 0 -1
|
|
// -1.2 1.2 -1
|
|
// -1.2 +Inf -1
|
|
//
|
|
// -0 -Inf 1
|
|
// -0 -1.2 1
|
|
// -0 -0 0
|
|
// -0 0 0
|
|
// -0 1.2 -1
|
|
// -0 +Inf -1
|
|
//
|
|
// 0 -Inf 1
|
|
// 0 -1.2 1
|
|
// 0 -0 0
|
|
// 0 0 0
|
|
// 0 1.2 -1
|
|
// 0 +Inf -1
|
|
//
|
|
// 1.2 -Inf 1
|
|
// 1.2 -1.2 1
|
|
// 1.2 -0 1
|
|
// 1.2 0 1
|
|
// 1.2 1.2 0
|
|
// 1.2 +Inf -1
|
|
//
|
|
// +Inf -Inf 1
|
|
// +Inf -1.2 1
|
|
// +Inf -0 1
|
|
// +Inf 0 1
|
|
// +Inf 1.2 1
|
|
// +Inf +Inf 0
|
|
}
|
|
|
|
func ExampleRoundingMode() {
|
|
operands := []float64{2.6, 2.5, 2.1, -2.1, -2.5, -2.6}
|
|
|
|
fmt.Print(" x")
|
|
for mode := big.ToNearestEven; mode <= big.ToPositiveInf; mode++ {
|
|
fmt.Printf(" %s", mode)
|
|
}
|
|
fmt.Println()
|
|
|
|
for _, f64 := range operands {
|
|
fmt.Printf("%4g", f64)
|
|
for mode := big.ToNearestEven; mode <= big.ToPositiveInf; mode++ {
|
|
// sample operands above require 2 bits to represent mantissa
|
|
// set binary precision to 2 to round them to integer values
|
|
f := new(big.Float).SetPrec(2).SetMode(mode).SetFloat64(f64)
|
|
fmt.Printf(" %*g", len(mode.String()), f)
|
|
}
|
|
fmt.Println()
|
|
}
|
|
|
|
// Output:
|
|
// x ToNearestEven ToNearestAway ToZero AwayFromZero ToNegativeInf ToPositiveInf
|
|
// 2.6 3 3 2 3 2 3
|
|
// 2.5 2 3 2 3 2 3
|
|
// 2.1 2 2 2 3 2 3
|
|
// -2.1 -2 -2 -2 -3 -3 -2
|
|
// -2.5 -2 -3 -2 -3 -3 -2
|
|
// -2.6 -3 -3 -2 -3 -3 -2
|
|
}
|