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Source file src/math/big/decimal_test.go

Documentation: math/big

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package big
     6  
     7  import (
     8  	"fmt"
     9  	"testing"
    10  )
    11  
    12  func TestDecimalString(t *testing.T) {
    13  	for _, test := range []struct {
    14  		x    decimal
    15  		want string
    16  	}{
    17  		{want: "0"},
    18  		{decimal{nil, 1000}, "0"}, // exponent of 0 is ignored
    19  		{decimal{[]byte("12345"), 0}, "0.12345"},
    20  		{decimal{[]byte("12345"), -3}, "0.00012345"},
    21  		{decimal{[]byte("12345"), +3}, "123.45"},
    22  		{decimal{[]byte("12345"), +10}, "1234500000"},
    23  	} {
    24  		if got := test.x.String(); got != test.want {
    25  			t.Errorf("%v == %s; want %s", test.x, got, test.want)
    26  		}
    27  	}
    28  }
    29  
    30  func TestDecimalInit(t *testing.T) {
    31  	for _, test := range []struct {
    32  		x     Word
    33  		shift int
    34  		want  string
    35  	}{
    36  		{0, 0, "0"},
    37  		{0, -100, "0"},
    38  		{0, 100, "0"},
    39  		{1, 0, "1"},
    40  		{1, 10, "1024"},
    41  		{1, 100, "1267650600228229401496703205376"},
    42  		{1, -100, "0.0000000000000000000000000000007888609052210118054117285652827862296732064351090230047702789306640625"},
    43  		{12345678, 8, "3160493568"},
    44  		{12345678, -8, "48225.3046875"},
    45  		{195312, 9, "99999744"},
    46  		{1953125, 9, "1000000000"},
    47  	} {
    48  		var d decimal
    49  		d.init(nat{test.x}.norm(), test.shift)
    50  		if got := d.String(); got != test.want {
    51  			t.Errorf("%d << %d == %s; want %s", test.x, test.shift, got, test.want)
    52  		}
    53  	}
    54  }
    55  
    56  func TestDecimalRounding(t *testing.T) {
    57  	for _, test := range []struct {
    58  		x              uint64
    59  		n              int
    60  		down, even, up string
    61  	}{
    62  		{0, 0, "0", "0", "0"},
    63  		{0, 1, "0", "0", "0"},
    64  
    65  		{1, 0, "0", "0", "10"},
    66  		{5, 0, "0", "0", "10"},
    67  		{9, 0, "0", "10", "10"},
    68  
    69  		{15, 1, "10", "20", "20"},
    70  		{45, 1, "40", "40", "50"},
    71  		{95, 1, "90", "100", "100"},
    72  
    73  		{12344999, 4, "12340000", "12340000", "12350000"},
    74  		{12345000, 4, "12340000", "12340000", "12350000"},
    75  		{12345001, 4, "12340000", "12350000", "12350000"},
    76  		{23454999, 4, "23450000", "23450000", "23460000"},
    77  		{23455000, 4, "23450000", "23460000", "23460000"},
    78  		{23455001, 4, "23450000", "23460000", "23460000"},
    79  
    80  		{99994999, 4, "99990000", "99990000", "100000000"},
    81  		{99995000, 4, "99990000", "100000000", "100000000"},
    82  		{99999999, 4, "99990000", "100000000", "100000000"},
    83  
    84  		{12994999, 4, "12990000", "12990000", "13000000"},
    85  		{12995000, 4, "12990000", "13000000", "13000000"},
    86  		{12999999, 4, "12990000", "13000000", "13000000"},
    87  	} {
    88  		x := nat(nil).setUint64(test.x)
    89  
    90  		var d decimal
    91  		d.init(x, 0)
    92  		d.roundDown(test.n)
    93  		if got := d.String(); got != test.down {
    94  			t.Errorf("roundDown(%d, %d) = %s; want %s", test.x, test.n, got, test.down)
    95  		}
    96  
    97  		d.init(x, 0)
    98  		d.round(test.n)
    99  		if got := d.String(); got != test.even {
   100  			t.Errorf("round(%d, %d) = %s; want %s", test.x, test.n, got, test.even)
   101  		}
   102  
   103  		d.init(x, 0)
   104  		d.roundUp(test.n)
   105  		if got := d.String(); got != test.up {
   106  			t.Errorf("roundUp(%d, %d) = %s; want %s", test.x, test.n, got, test.up)
   107  		}
   108  	}
   109  }
   110  
   111  var sink string
   112  
   113  func BenchmarkDecimalConversion(b *testing.B) {
   114  	for i := 0; i < b.N; i++ {
   115  		for shift := -100; shift <= +100; shift++ {
   116  			var d decimal
   117  			d.init(natOne, shift)
   118  			sink = d.String()
   119  		}
   120  	}
   121  }
   122  
   123  func BenchmarkFloatString(b *testing.B) {
   124  	x := new(Float)
   125  	for _, prec := range []uint{1e2, 1e3, 1e4, 1e5} {
   126  		x.SetPrec(prec).SetRat(NewRat(1, 3))
   127  		b.Run(fmt.Sprintf("%v", prec), func(b *testing.B) {
   128  			b.ReportAllocs()
   129  			for i := 0; i < b.N; i++ {
   130  				sink = x.String()
   131  			}
   132  		})
   133  	}
   134  }
   135  

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