add Rat methods SetFrac, Neg, and IsInt

Author: jamesadney

rat.go

@@ -95,6 +95,20 @@ func (q *Rat) SetUint(x, y uint) *Rat {
 	return q
 }
 
+// SetFrac sets z to a/b and returns z.
+func (z *Rat) SetFrac(a, b *Int) *Rat {
+	a.doinit()
+	b.doinit()
+
+	temp_a := new(Rat).SetInt(a)
+	temp_b := new(Rat).SetInt(b)
+	z.Quo(temp_a, temp_b)
+	temp_a.Clear()
+	temp_b.Clear()
+
+	return z
+}
+
 // SetInt sets q to x and returns q.
 func (q *Rat) SetInt(x *Int) *Rat {
 	q.doinit()
@@ -224,6 +238,14 @@ func (q *Rat) Mul(x, y *Rat) *Rat {
 	return q
 }
 
+// Neg sets z to -x and returns z.
+func (z *Rat) Neg(x *Rat) *Rat {
+	z.doinit()
+	x.doinit()
+	C.mpq_neg(&z.i[0], &x.i[0])
+	return z
+}
+
 func (q *Rat) Quo(x, y *Rat) *Rat {
 	x.doinit()
 	y.doinit()
@@ -294,6 +316,16 @@ func CmpRatInt64(q *Rat, x int64, y uint) int {
 	//return int(C.mpq_cmp_ui(&x.i[0], C.long(x), C.ulong(y)))
 }
 
+// IsInt returns true if the denominator of x is 1.
+func (q *Rat) IsInt() bool {
+	q.doinit()
+	C.mpq_canonicalize(&q.i[0])
+	if q.Denom().Cmp(intOne) == 0 {
+		return true
+	}
+	return false
+}
+
 // Sign returns:
 //
 //	-1 if x <  0

rat_test.go

@@ -137,6 +137,72 @@ func TestRatCmp(t *testing.T) {
 	}
 }
 
+func TestIsInt(t *testing.T) {
+	one := NewInt(1)
+	for _, a := range setStringTests {
+		x, ok := new(Rat).SetString(a.in)
+		if !ok {
+			continue
+		}
+		i := x.IsInt()
+		e := x.Denom().Cmp(one) == 0
+		if i != e {
+			t.Errorf("got IsInt(%v) == %v; want %v", x, i, e)
+		}
+	}
+}
+
+func TestRatAbs(t *testing.T) {
+	zero := new(Rat)
+	for _, a := range setStringTests {
+		x, ok := new(Rat).SetString(a.in)
+		if !ok {
+			continue
+		}
+		e := new(Rat).Set(x)
+		if e.Cmp(zero) < 0 {
+			e.Sub(zero, e)
+		}
+		z := new(Rat).Abs(x)
+		if z.Cmp(e) != 0 {
+			t.Errorf("got Abs(%v) = %v; want %v", x, z, e)
+		}
+	}
+}
+
+func TestRatNeg(t *testing.T) {
+	zero := new(Rat)
+	for _, a := range setStringTests {
+		x, ok := new(Rat).SetString(a.in)
+		if !ok {
+			continue
+		}
+		e := new(Rat).Sub(zero, x)
+		z := new(Rat).Neg(x)
+		if z.Cmp(e) != 0 {
+			t.Errorf("got Neg(%v) = %v; want %v", x, z, e)
+		}
+	}
+}
+
+func TestRatInv(t *testing.T) {
+	zero := new(Rat)
+	for _, a := range setStringTests {
+		x, ok := new(Rat).SetString(a.in)
+		if !ok {
+			continue
+		}
+		if x.Cmp(zero) == 0 {
+			continue // avoid division by zero
+		}
+		e := new(Rat).SetFrac(x.Denom(), x.Num())
+		z := new(Rat).Inv(x)
+		if z.Cmp(e) != 0 {
+			t.Errorf("got Inv(%v) = %v; want %v", x, z, e)
+		}
+	}
+}
+
 type ratBinFun func(z, x, y *Rat) *Rat
 type ratBinArg struct {
 	x, y, z string