github.com/ccccaoqing/test@v0.0.0-20220510085219-3985d23445c0/src/math/floor.go (about)

     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  func Floor(x float64) float64
    14  
    15  func floor(x float64) float64 {
    16  	if x == 0 || IsNaN(x) || IsInf(x, 0) {
    17  		return x
    18  	}
    19  	if x < 0 {
    20  		d, fract := Modf(-x)
    21  		if fract != 0.0 {
    22  			d = d + 1
    23  		}
    24  		return -d
    25  	}
    26  	d, _ := Modf(x)
    27  	return d
    28  }
    29  
    30  // Ceil returns the least integer value greater than or equal to x.
    31  //
    32  // Special cases are:
    33  //	Ceil(±0) = ±0
    34  //	Ceil(±Inf) = ±Inf
    35  //	Ceil(NaN) = NaN
    36  func Ceil(x float64) float64
    37  
    38  func ceil(x float64) float64 {
    39  	return -Floor(-x)
    40  }
    41  
    42  // Trunc returns the integer value of x.
    43  //
    44  // Special cases are:
    45  //	Trunc(±0) = ±0
    46  //	Trunc(±Inf) = ±Inf
    47  //	Trunc(NaN) = NaN
    48  func Trunc(x float64) float64
    49  
    50  func trunc(x float64) float64 {
    51  	if x == 0 || IsNaN(x) || IsInf(x, 0) {
    52  		return x
    53  	}
    54  	d, _ := Modf(x)
    55  	return d
    56  }