| // 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) | |
| } | |
| } |