Adding upstream version 1.22.1.upstream/1.22.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 141 insertions, 0 deletions

diff --git a/src/math/big/floatexample_test.go b/src/math/big/floatexample_test.go
new file mode 100644
index 0000000..0c6668c
--- /dev/null
+++ b/src/math/big/floatexample_test.go
@@ -0,0 +1,141 @@
+// 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.
+
+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
+}