// run | |
// Copyright 2015 The Go Authors. All rights reserved. | |
// Use of this source code is governed by a BSD-style | |
// license that can be found in the LICENSE file. | |
// This test computes the precision of the compiler's internal multiprecision floats. | |
package main | |
import ( | |
"fmt" | |
"math" | |
"runtime" | |
) | |
const ulp = (1.0 + (2.0 / 3.0)) - (5.0 / 3.0) | |
func main() { | |
// adjust precision depending on compiler | |
var prec float64 | |
switch runtime.Compiler { | |
case "gc": | |
prec = 512 | |
case "gccgo": | |
prec = 256 | |
default: | |
// unknown compiler | |
return | |
} | |
p := 1 - math.Log(math.Abs(ulp))/math.Log(2) | |
if math.Abs(p-prec) > 1e-10 { | |
fmt.Printf("BUG: got %g; want %g\n", p, prec) | |
} | |
} |