Initial data commit

Task/Exponentiation-operator/Go/exponentiation-operator.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+    "errors"
+    "fmt"
+)
+
+func expI(b, p int) (int, error) {
+    if p < 0 {
+        return 0, errors.New("negative power not allowed")
+    }
+    r := 1
+    for i := 1; i <= p; i++ {
+        r *= b
+    }
+    return r, nil
+}
+
+func expF(b float32, p int) float32 {
+    var neg bool
+    if p < 0 {
+        neg = true
+        p = -p
+    }
+    r := float32(1)
+    for pow := b; p > 0; pow *= pow {
+        if p&1 == 1 {
+            r *= pow
+        }
+        p >>= 1
+    }
+    if neg {
+        r = 1 / r
+    }
+    return r
+}
+
+func main() {
+    ti := func(b, p int) {
+        fmt.Printf("%d^%d: ", b, p)
+        e, err := expI(b, p)
+        if err != nil {
+            fmt.Println(err)
+        } else {
+            fmt.Println(e)
+        }
+    }
+
+    fmt.Println("expI tests")
+    ti(2, 10)
+    ti(2, -10)
+    ti(-2, 10)
+    ti(-2, 11)
+    ti(11, 0)
+
+    fmt.Println("overflow undetected")
+    ti(10, 10)
+
+    tf := func(b float32, p int) {
+        fmt.Printf("%g^%d: %g\n", b, p, expF(b, p))
+    }
+
+    fmt.Println("\nexpF tests:")
+    tf(2, 10)
+    tf(2, -10)
+    tf(-2, 10)
+    tf(-2, 11)
+    tf(11, 0)
+
+    fmt.Println("disallowed in expI, allowed here")
+    tf(0, -1)
+
+    fmt.Println("other interesting cases for 32 bit float type")
+    tf(10, 39)
+    tf(10, -39)
+    tf(-10, 39)
+}