_cmptest: mathbigdemo

_cmptest/_goconstdemo/goconst.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"go/constant"
+	"go/token"
+)
+
+func main() {
+	// Create the complex number 2.3 + 5i.
+	ar := constant.MakeFloat64(2.3)
+	ai := constant.MakeImag(constant.MakeInt64(5))
+	a := constant.BinaryOp(ar, token.ADD, ai)
+
+	// Compute (2.3 + 5i) * 11.
+	b := constant.MakeUint64(11)
+	c := constant.BinaryOp(a, token.MUL, b)
+
+	// Convert c into a complex128.
+	Ar, exact := constant.Float64Val(constant.Real(c))
+	if !exact {
+		fmt.Printf("Could not represent real part %s exactly as float64\n", constant.Real(c))
+	}
+	Ai, exact := constant.Float64Val(constant.Imag(c))
+	if !exact {
+		fmt.Printf("Could not represent imaginary part %s as exactly as float64\n", constant.Imag(c))
+	}
+	C := complex(Ar, Ai)
+
+	fmt.Println("literal", 25.3+55i)
+	fmt.Println("go/constant", c)
+	fmt.Println("complex128", C)
+}

_cmptest/mathbigdemo/big.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"math/big"
+)
+
+func main() {
+	// Initialize two big ints with the first two numbers in the sequence.
+	a := big.NewInt(0)
+	b := big.NewInt(1)
+
+	// Initialize limit as 10^99, the smallest integer with 100 digits.
+	var limit big.Int
+	limit.Exp(big.NewInt(10), big.NewInt(99), nil)
+
+	// Loop while a is smaller than 1e100.
+	for a.Cmp(&limit) < 0 {
+		// Compute the next Fibonacci number, storing it in a.
+		a.Add(a, b)
+		// Swap a and b so that b is the next number in the sequence.
+		a, b = b, a
+	}
+	fmt.Println(a) // 100-digit Fibonacci number
+}