Merge pull request #2 from txaty/bugfix/hurwitz_prod

Fix Hurwitz integer product issue

Author: Tommy TIAN

README.md

@@ -2,7 +2,7 @@
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/txaty/go-bigcomplex.svg)](https://pkg.go.dev/github.com/txaty/go-bigcomplex)
 [![Go Report Card](https://goreportcard.com/badge/github.com/txaty/go-bigcomplex)](https://goreportcard.com/report/github.com/txaty/go-bigcomplex)
-![Coverage](https://img.shields.io/badge/Coverage-47.4%25-yellow)
+![Coverage](https://img.shields.io/badge/Coverage-45.8%25-yellow)
 
 Big complex number calculation library for Go (with [math/big](https://pkg.go.dev/math/big)).
 

hurwitz_integer.go

@@ -298,22 +298,7 @@ func (h *HurwitzInt) Copy() *HurwitzInt {
 // the product (a1 + b1j + c1k + d1)(a2 + b2j + c2k + d2) is determined by the products of the
 // basis elements and the distributive law
 func (h *HurwitzInt) Prod(a, b *HurwitzInt) *HurwitzInt {
-	if h.dblR == nil {
-		h.dblR = new(big.Int)
-	}
-	r := h.dblR
-	if h.dblI == nil {
-		h.dblI = new(big.Int)
-	}
-	i := h.dblI
-	if h.dblJ == nil {
-		h.dblJ = new(big.Int)
-	}
-	j := h.dblJ
-	if h.dblK == nil {
-		h.dblK = new(big.Int)
-	}
-	k := h.dblK
+	r, i, j, k := new(big.Int), new(big.Int), new(big.Int), new(big.Int)
 	opt := iPool.Get().(*big.Int)
 	defer iPool.Put(opt)
 	// 1 part
@@ -344,6 +329,8 @@ func (h *HurwitzInt) Prod(a, b *HurwitzInt) *HurwitzInt {
 	k.Add(k, opt.Mul(a.dblK, b.dblR))
 	k.Rsh(k, 1)
 
+	h.dblR, h.dblI, h.dblJ, h.dblK = r, i, j, k
+
 	return h
 }
 

hurwitz_integer_test.go

@@ -24,7 +24,7 @@ func TestHurwitzInt_Prod(t *testing.T) {
 		want   *HurwitzInt
 	}{
 		{
-			name: "test_(1+i+j+k)+(1+i+j+k)",
+			name: "test_(1+i+j+k) * (1+i+j+k)",
 			fields: fields{
 				dblR: nil,
 				dblI: nil,
@@ -37,6 +37,20 @@ func TestHurwitzInt_Prod(t *testing.T) {
 			},
 			want: NewHurwitzInt(big.NewInt(-2), big.NewInt(2), big.NewInt(2), big.NewInt(2), false),
 		},
+		{
+			name: "test_2i * 1",
+			fields: fields{
+				dblR: nil,
+				dblI: nil,
+				dblJ: nil,
+				dblK: nil,
+			},
+			args: args{
+				a: NewHurwitzInt(big.NewInt(0), big.NewInt(2), big.NewInt(0), big.NewInt(0), false),
+				b: NewHurwitzInt(big.NewInt(1), big.NewInt(0), big.NewInt(0), big.NewInt(0), false),
+			},
+			want: NewHurwitzInt(big.NewInt(0), big.NewInt(2), big.NewInt(0), big.NewInt(0), false),
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {