Fix mod when the divisor is slightly greater than the half of dividend (

#312) (#317)
shopspring · Jan 10, 2024 · 7b4ffbc · 7b4ffbc
1 parent 1df8fb3
commit 7b4ffbc
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Showing 2 changed files with 4 additions and 2 deletions.
diff --git a/decimal.go b/decimal.go
@@ -626,8 +626,8 @@ func (d Decimal) DivRound(d2 Decimal, precision int32) Decimal {
 
 // Mod returns d % d2.
 func (d Decimal) Mod(d2 Decimal) Decimal {
-	quo := d.DivRound(d2, -d.exp+1).Truncate(0)
-	return d.Sub(d2.Mul(quo))
+	_, r := d.QuoRem(d2, 0)
+	return r
 }
 
 // Pow returns d to the power d2

diff --git a/decimal_test.go b/decimal_test.go
@@ -2147,6 +2147,8 @@ func TestDecimal_Mod(t *testing.T) {
 		Inp{"-7.5", "2"}:                        "-1.5",
 		Inp{"7.5", "-2"}:                        "1.5",
 		Inp{"-7.5", "-2"}:                       "-1.5",
+		Inp{"41", "21"}:                         "20",
+		Inp{"400000000001", "200000000001"}:     "200000000000",
 	}
 
 	for inp, res := range inputs {