libgo/go/math/floor.go

   1 // Copyright 2009-2010 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package math
   6
   7 // Floor returns the greatest integer value less than or equal to x.
   8 //
   9 // Special cases are:
  10 //      Floor(±0) = ±0
  11 //      Floor(±Inf) = ±Inf
  12 //      Floor(NaN) = NaN
  13
  14 //extern floor
  15 func libc_floor(float64) float64
  16
  17 func Floor(x float64) float64 {
  18         return libc_floor(x)
  19 }
  20
  21 func floor(x float64) float64 {
  22         if x == 0 || IsNaN(x) || IsInf(x, 0) {
  23                 return x
  24         }
  25         if x < 0 {
  26                 d, fract := Modf(-x)
  27                 if fract != 0.0 {
  28                         d = d + 1
  29                 }
  30                 return -d
  31         }
  32         d, _ := Modf(x)
  33         return d
  34 }
  35
  36 // Ceil returns the least integer value greater than or equal to x.
  37 //
  38 // Special cases are:
  39 //      Ceil(±0) = ±0
  40 //      Ceil(±Inf) = ±Inf
  41 //      Ceil(NaN) = NaN
  42
  43 //extern ceil
  44 func libc_ceil(float64) float64
  45
  46 func Ceil(x float64) float64 {
  47         return libc_ceil(x)
  48 }
  49
  50 func ceil(x float64) float64 {
  51         return -Floor(-x)
  52 }
  53
  54 // Trunc returns the integer value of x.
  55 //
  56 // Special cases are:
  57 //      Trunc(±0) = ±0
  58 //      Trunc(±Inf) = ±Inf
  59 //      Trunc(NaN) = NaN
  60
  61 func Trunc(x float64) float64 {
  62         return trunc(x)
  63 }
  64
  65 func trunc(x float64) float64 {
  66         if x == 0 || IsNaN(x) || IsInf(x, 0) {
  67                 return x
  68         }
  69         d, _ := Modf(x)
  70         return d
  71 }