Data commit

Task/Extreme-floating-point-values/Go/extreme-floating-point-values.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+    "fmt"
+    "math"
+)
+
+func main() {
+    // compute "extreme values" from non-extreme values
+    var zero float64                         // zero is handy.
+    var negZero, posInf, negInf, nan float64 // values to compute.
+    negZero = zero * -1
+    posInf = 1 / zero
+    negInf = -1 / zero
+    nan = zero / zero
+
+    // print extreme values stored in variables
+    fmt.Println(negZero, posInf, negInf, nan)
+
+    // directly obtain extreme values
+    fmt.Println(math.Float64frombits(1<<63),
+        math.Inf(1), math.Inf(-1), math.NaN())
+
+    // validate some arithmetic on extreme values
+    fmt.Println()
+    validateNaN(negInf+posInf, "-Inf + Inf")
+    validateNaN(0*posInf, "0 * Inf")
+    validateNaN(posInf/posInf, "Inf / Inf")
+    // mod is specifically named in "What every computer scientist..."
+    // Go math package doc lists many special cases for other package functions.
+    validateNaN(math.Mod(posInf, 1), "Inf % 1")
+    validateNaN(1+nan, "1 + NaN")
+    validateZero(1/posInf, "1 / Inf")
+    validateGT(posInf, math.MaxFloat64, "Inf > max value")
+    validateGT(-math.MaxFloat64, negInf, "-Inf < max neg value")
+    validateNE(nan, nan, "NaN != NaN")
+    validateEQ(negZero, 0, "-0 == 0")
+}
+
+func validateNaN(n float64, op string) {
+    if math.IsNaN(n) {
+        fmt.Println(op, "-> NaN")
+    } else {
+        fmt.Println("!!! Expected NaN from", op, "  Found", n)
+    }
+}
+
+func validateZero(n float64, op string) {
+    if n == 0 {
+        fmt.Println(op, "-> 0")
+    } else {
+        fmt.Println("!!! Expected 0 from", op, "  Found", n)
+    }
+}
+
+func validateGT(a, b float64, op string) {
+    if a > b {
+        fmt.Println(op)
+    } else {
+        fmt.Println("!!! Expected", op, "  Found not true.")
+    }
+}
+
+func validateNE(a, b float64, op string) {
+    if a == b {
+        fmt.Println("!!! Expected", op, "  Found not true.")
+    } else {
+        fmt.Println(op)
+    }
+}
+
+func validateEQ(a, b float64, op string) {
+    if a == b {
+        fmt.Println(op)
+    } else {
+        fmt.Println("!!! Expected", op, "  Found not true.")
+    }
+}