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Source file src/runtime/float.go

Documentation: runtime

  // Copyright 2017 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.
  
  package runtime
  
  import "unsafe"
  
  var inf = float64frombits(0x7FF0000000000000)
  
  // isNaN reports whether f is an IEEE 754 ``not-a-number'' value.
  func isNaN(f float64) (is bool) {
  	// IEEE 754 says that only NaNs satisfy f != f.
  	return f != f
  }
  
  // isFinite reports whether f is neither NaN nor an infinity.
  func isFinite(f float64) bool {
  	return !isNaN(f - f)
  }
  
  // isInf reports whether f is an infinity.
  func isInf(f float64) bool {
  	return !isNaN(f) && !isFinite(f)
  }
  
  // Abs returns the absolute value of x.
  //
  // Special cases are:
  //	Abs(±Inf) = +Inf
  //	Abs(NaN) = NaN
  func abs(x float64) float64 {
  	const sign = 1 << 63
  	return float64frombits(float64bits(x) &^ sign)
  }
  
  // copysign returns a value with the magnitude
  // of x and the sign of y.
  func copysign(x, y float64) float64 {
  	const sign = 1 << 63
  	return float64frombits(float64bits(x)&^sign | float64bits(y)&sign)
  }
  
  // Float64bits returns the IEEE 754 binary representation of f.
  func float64bits(f float64) uint64 {
  	return *(*uint64)(unsafe.Pointer(&f))
  }
  
  // Float64frombits returns the floating point number corresponding
  // the IEEE 754 binary representation b.
  func float64frombits(b uint64) float64 {
  	return *(*float64)(unsafe.Pointer(&b))
  }
  

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