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📄 accuracy_string.go(647 B)
📄 alias_test.go(8.81 KB)
📄 arith.go(8.28 KB)
📄 arith_386.s(4.04 KB)
📄 arith_amd64.go(278 B)
📄 arith_amd64.s(9.07 KB)
📄 arith_arm.s(4 KB)
📄 arith_arm64.s(11.85 KB)
📄 arith_decl.go(686 B)
📄 arith_decl_pure.go(1.01 KB)
📄 arith_decl_s390x.go(503 B)
📄 arith_loong64.s(749 B)
📄 arith_mips64x.s(763 B)
📄 arith_mipsx.s(759 B)
📄 arith_ppc64x.s(16.4 KB)
📄 arith_riscv64.s(750 B)
📄 arith_s390x.s(20.29 KB)
📄 arith_s390x_test.go(770 B)
📄 arith_test.go(19.88 KB)
📄 arith_wasm.s(613 B)
📄 bits_test.go(5.07 KB)
📄 calibrate_test.go(4.63 KB)
📄 decimal.go(6.63 KB)
📄 decimal_test.go(3.33 KB)
📄 doc.go(3.8 KB)
📄 example_rat_test.go(1.68 KB)
📄 example_test.go(4.05 KB)
📄 float.go(44.55 KB)
📄 float_test.go(51.94 KB)
📄 floatconv.go(8.35 KB)
📄 floatconv_test.go(24.27 KB)
📄 floatexample_test.go(3.63 KB)
📄 floatmarsh.go(3.65 KB)
📄 floatmarsh_test.go(4.51 KB)
📄 ftoa.go(13.5 KB)
📄 gcd_test.go(2.16 KB)
📄 hilbert_test.go(2.88 KB)
📄 int.go(33.21 KB)
📄 int_test.go(58.47 KB)
📄 intconv.go(6.7 KB)
📄 intconv_test.go(10.01 KB)
📄 intmarsh.go(2.19 KB)
📄 intmarsh_test.go(3.07 KB)
📄 link_test.go(1.4 KB)
📄 nat.go(31.81 KB)
📄 nat_test.go(26.22 KB)
📄 natconv.go(14.56 KB)
📄 natconv_test.go(16.85 KB)
📄 natdiv.go(34.36 KB)
📄 prime.go(10.39 KB)
📄 prime_test.go(7.1 KB)
📄 rat.go(13.48 KB)
📄 rat_test.go(18.89 KB)
📄 ratconv.go(12.35 KB)
📄 ratconv_test.go(19.31 KB)
📄 ratmarsh.go(2.23 KB)
📄 ratmarsh_test.go(3.34 KB)
📄 roundingmode_string.go(819 B)
📄 sqrt.go(2.79 KB)
📄 sqrt_test.go(4.81 KB)

Editing: example_test.go

// Copyright 2012 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"
	"log"
	"math"
	"math/big"
)

func ExampleRat_SetString() {
	r := new(big.Rat)
	r.SetString("355/113")
	fmt.Println(r.FloatString(3))
	// Output: 3.142
}

func ExampleInt_SetString() {
	i := new(big.Int)
	i.SetString("644", 8) // octal
	fmt.Println(i)
	// Output: 420
}

func ExampleFloat_SetString() {
	f := new(big.Float)
	f.SetString("3.14159")
	fmt.Println(f)
	// Output: 3.14159
}

func ExampleRat_Scan() {
	// The Scan function is rarely used directly;
	// the fmt package recognizes it as an implementation of fmt.Scanner.
	r := new(big.Rat)
	_, err := fmt.Sscan("1.5000", r)
	if err != nil {
		log.Println("error scanning value:", err)
	} else {
		fmt.Println(r)
	}
	// Output: 3/2
}

func ExampleInt_Scan() {
	// The Scan function is rarely used directly;
	// the fmt package recognizes it as an implementation of fmt.Scanner.
	i := new(big.Int)
	_, err := fmt.Sscan("18446744073709551617", i)
	if err != nil {
		log.Println("error scanning value:", err)
	} else {
		fmt.Println(i)
	}
	// Output: 18446744073709551617
}

func ExampleFloat_Scan() {
	// The Scan function is rarely used directly;
	// the fmt package recognizes it as an implementation of fmt.Scanner.
	f := new(big.Float)
	_, err := fmt.Sscan("1.19282e99", f)
	if err != nil {
		log.Println("error scanning value:", err)
	} else {
		fmt.Println(f)
	}
	// Output: 1.19282e+99
}

// This example demonstrates how to use big.Int to compute the smallest
// Fibonacci number with 100 decimal digits and to test whether it is prime.
func Example_fibonacci() {
	// Initialize two big ints with the first two numbers in the sequence.
	a := big.NewInt(0)
	b := big.NewInt(1)

// Initialize limit as 10^99, the smallest integer with 100 digits.
	var limit big.Int
	limit.Exp(big.NewInt(10), big.NewInt(99), nil)

// Loop while a is smaller than 1e100.
	for a.Cmp(&limit) < 0 {
		// Compute the next Fibonacci number, storing it in a.
		a.Add(a, b)
		// Swap a and b so that b is the next number in the sequence.
		a, b = b, a
	}
	fmt.Println(a) // 100-digit Fibonacci number

// Test a for primality.
	// (ProbablyPrimes' argument sets the number of Miller-Rabin
	// rounds to be performed. 20 is a good value.)
	fmt.Println(a.ProbablyPrime(20))

// Output:
	// 1344719667586153181419716641724567886890850696275767987106294472017884974410332069524504824747437757
	// false
}

// This example shows how to use big.Float to compute the square root of 2 with
// a precision of 200 bits, and how to print the result as a decimal number.
func Example_sqrt2() {
	// We'll do computations with 200 bits of precision in the mantissa.
	const prec = 200

// Compute the square root of 2 using Newton's Method. We start with
	// an initial estimate for sqrt(2), and then iterate:
	//     x_{n+1} = 1/2 * ( x_n + (2.0 / x_n) )

// Since Newton's Method doubles the number of correct digits at each
	// iteration, we need at least log_2(prec) steps.
	steps := int(math.Log2(prec))

// Initialize values we need for the computation.
	two := new(big.Float).SetPrec(prec).SetInt64(2)
	half := new(big.Float).SetPrec(prec).SetFloat64(0.5)

// Use 1 as the initial estimate.
	x := new(big.Float).SetPrec(prec).SetInt64(1)

// We use t as a temporary variable. There's no need to set its precision
	// since big.Float values with unset (== 0) precision automatically assume
	// the largest precision of the arguments when used as the result (receiver)
	// of a big.Float operation.
	t := new(big.Float)

// Iterate.
	for i := 0; i <= steps; i++ {
		t.Quo(two, x)  // t = 2.0 / x_n
		t.Add(x, t)    // t = x_n + (2.0 / x_n)
		x.Mul(half, t) // x_{n+1} = 0.5 * t
	}

// We can use the usual fmt.Printf verbs since big.Float implements fmt.Formatter
	fmt.Printf("sqrt(2) = %.50f\n", x)

// Print the error between 2 and x*x.
	t.Mul(x, x) // t = x*x
	fmt.Printf("error = %e\n", t.Sub(two, t))

// Output:
	// sqrt(2) = 1.41421356237309504880168872420969807856967187537695
	// error = 0.000000e+00
}

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Editing: example_test.go

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