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Author SHA1 Message Date
Mateusz Woś
0e69d5cd53
Run CI on both push to origin branches and pull requests (#360) 2024-04-04 16:35:31 +02:00
Philip Dubé
bf7794e1a8
Optimize NumDigits method (#356) 2024-04-04 16:14:38 +02:00
3 changed files with 62 additions and 11 deletions

View file

@ -1,5 +1,9 @@
name: ci name: ci
on: [push] on:
push:
branches:
- master
pull_request:
jobs: jobs:
ci-job: ci-job:
runs-on: ubuntu-latest runs-on: ubuntu-latest

View file

@ -1224,14 +1224,33 @@ func (d Decimal) Ln(precision int32) (Decimal, error) {
} }
// NumDigits returns the number of digits of the decimal coefficient (d.Value) // NumDigits returns the number of digits of the decimal coefficient (d.Value)
// Note: Current implementation is extremely slow for large decimals and/or decimals with large fractional part
func (d Decimal) NumDigits() int { func (d Decimal) NumDigits() int {
d.ensureInitialized() if d.value == nil {
// Note(mwoss): It can be optimized, unnecessary cast of big.Int to string return 1
if d.IsNegative() {
return len(d.value.String()) - 1
} }
return len(d.value.String())
if d.value.IsInt64() {
i64 := d.value.Int64()
// restrict fast path to integers with exact conversion to float64
if i64 <= (1<<53) && i64 >= -(1<<53) {
if i64 == 0 {
return 1
}
return int(math.Log10(math.Abs(float64(i64)))) + 1
}
}
estimatedNumDigits := int(float64(d.value.BitLen()) / math.Log2(10))
// estimatedNumDigits (lg10) may be off by 1, need to verify
digitsBigInt := big.NewInt(int64(estimatedNumDigits))
errorCorrectionUnit := digitsBigInt.Exp(tenInt, digitsBigInt, nil)
if d.value.CmpAbs(errorCorrectionUnit) >= 0 {
return estimatedNumDigits + 1
}
return estimatedNumDigits
} }
// IsInteger returns true when decimal can be represented as an integer value, otherwise, it returns false. // IsInteger returns true when decimal can be represented as an integer value, otherwise, it returns false.

View file

@ -121,6 +121,34 @@ func BenchmarkDecimal_RoundCash_Five(b *testing.B) {
} }
} }
func numDigits(b *testing.B, want int, val Decimal) {
b.Helper()
for i := 0; i < b.N; i++ {
if have := val.NumDigits(); have != want {
b.Fatalf("\nHave: %d\nWant: %d", have, want)
}
}
}
func BenchmarkDecimal_NumDigits10(b *testing.B) {
numDigits(b, 10, New(3478512345, -3))
}
func BenchmarkDecimal_NumDigits100(b *testing.B) {
s := make([]byte, 102)
for i := range s {
s[i] = byte('0' + i%10)
}
s[0] = '-'
s[100] = '.'
d, err := NewFromString(string(s))
if err != nil {
b.Log(d)
b.Error(err)
}
numDigits(b, 100, d)
}
func Benchmark_Cmp(b *testing.B) { func Benchmark_Cmp(b *testing.B) {
decimals := DecimalSlice([]Decimal{}) decimals := DecimalSlice([]Decimal{})
for i := 0; i < 1000000; i++ { for i := 0; i < 1000000; i++ {
@ -132,7 +160,7 @@ func Benchmark_Cmp(b *testing.B) {
} }
} }
func Benchmark_decimal_Decimal_Add_different_precision(b *testing.B) { func BenchmarkDecimal_Add_different_precision(b *testing.B) {
d1 := NewFromFloat(1000.123) d1 := NewFromFloat(1000.123)
d2 := NewFromFloat(500).Mul(NewFromFloat(0.12)) d2 := NewFromFloat(500).Mul(NewFromFloat(0.12))
@ -143,7 +171,7 @@ func Benchmark_decimal_Decimal_Add_different_precision(b *testing.B) {
} }
} }
func Benchmark_decimal_Decimal_Sub_different_precision(b *testing.B) { func BenchmarkDecimal_Sub_different_precision(b *testing.B) {
d1 := NewFromFloat(1000.123) d1 := NewFromFloat(1000.123)
d2 := NewFromFloat(500).Mul(NewFromFloat(0.12)) d2 := NewFromFloat(500).Mul(NewFromFloat(0.12))
@ -154,7 +182,7 @@ func Benchmark_decimal_Decimal_Sub_different_precision(b *testing.B) {
} }
} }
func Benchmark_decimal_Decimal_Add_same_precision(b *testing.B) { func BenchmarkDecimal_Add_same_precision(b *testing.B) {
d1 := NewFromFloat(1000.123) d1 := NewFromFloat(1000.123)
d2 := NewFromFloat(500.123) d2 := NewFromFloat(500.123)
@ -165,7 +193,7 @@ func Benchmark_decimal_Decimal_Add_same_precision(b *testing.B) {
} }
} }
func Benchmark_decimal_Decimal_Sub_same_precision(b *testing.B) { func BenchmarkDecimal_Sub_same_precision(b *testing.B) {
d1 := NewFromFloat(1000.123) d1 := NewFromFloat(1000.123)
d2 := NewFromFloat(500.123) d2 := NewFromFloat(500.123)