Initial commit

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

common/maths/decimal.go

@@ -0,0 +1,78 @@
+package maths
+
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/shopspring/decimal"
+)
+
+// 保留2位小数
+func Decimal2Bit(value float64) float64 {
+	data, _ := strconv.ParseFloat(fmt.Sprintf("%.2f", value), 64)
+	return data
+}
+
+// 保留4位小数
+func Decimal4Bit(value float64) float64 {
+	data, _ := strconv.ParseFloat(fmt.Sprintf("%.4f", value), 64)
+	return data
+}
+
+// 保留6位小数
+func Decimal6Bit(value float64) float64 {
+	data, _ := strconv.ParseFloat(fmt.Sprintf("%.6f", value), 64)
+	return data
+}
+
+// 相乘
+func DecimalMul(dec1, dec2 string) (string, error) {
+	n1, err := decimal.NewFromString(dec1)
+	if err != nil {
+		return "", err
+	}
+	n2, err := decimal.NewFromString(dec2)
+	if err != nil {
+		return "", err
+	}
+	return n1.Mul(n2).String(), nil
+}
+
+// 相加
+func DecimalAdd(dec1, dec2 string) (string, error) {
+	n1, err := decimal.NewFromString(dec1)
+	if err != nil {
+		return "", err
+	}
+	n2, err := decimal.NewFromString(dec2)
+	if err != nil {
+		return "", err
+	}
+	return n1.Add(n2).String(), nil
+}
+
+// 相除
+func DecimalDiv(dec1, dec2 string) (string, error) {
+	n1, err := decimal.NewFromString(dec1)
+	if err != nil {
+		return "", err
+	}
+	n2, err := decimal.NewFromString(dec2)
+	if err != nil {
+		return "", err
+	}
+	return n1.Div(n2).String(), nil
+}
+
+// 相减
+func DecimalSub(dec1, dec2 string) (string, error) {
+	n1, err := decimal.NewFromString(dec1)
+	if err != nil {
+		return "", err
+	}
+	n2, err := decimal.NewFromString("-" + dec2)
+	if err != nil {
+		return "", err
+	}
+	return n1.Add(n2).String(), nil
+}