github.com/primecitizens/pcz/std@v0.2.1/core/math/const.go (about)

     1  // SPDX-License-Identifier: Apache-2.0
     2  // Copyright 2023 The Prime Citizens
     3  //
     4  // Copyright 2018 The Go Authors. All rights reserved.
     5  // Use of this source code is governed by a BSD-style
     6  // license that can be found in the LICENSE file.
     7  
     8  package math
     9  
    10  import "unsafe"
    11  
    12  // Mathematical constants.
    13  const (
    14  	E   = 2.71828182845904523536028747135266249775724709369995957496696763 // https://oeis.org/A001113
    15  	Pi  = 3.14159265358979323846264338327950288419716939937510582097494459 // https://oeis.org/A000796
    16  	Phi = 1.61803398874989484820458683436563811772030917980576286213544862 // https://oeis.org/A001622
    17  
    18  	Sqrt2   = 1.41421356237309504880168872420969807856967187537694807317667974 // https://oeis.org/A002193
    19  	SqrtE   = 1.64872127070012814684865078781416357165377610071014801157507931 // https://oeis.org/A019774
    20  	SqrtPi  = 1.77245385090551602729816748334114518279754945612238712821380779 // https://oeis.org/A002161
    21  	SqrtPhi = 1.27201964951406896425242246173749149171560804184009624861664038 // https://oeis.org/A139339
    22  
    23  	Ln2    = 0.693147180559945309417232121458176568075500134360255254120680009 // https://oeis.org/A002162
    24  	Log2E  = 1 / Ln2
    25  	Ln10   = 2.30258509299404568401799145468436420760110148862877297603332790 // https://oeis.org/A002392
    26  	Log10E = 1 / Ln10
    27  )
    28  
    29  // Floating-point limit values.
    30  // Max is the largest finite value representable by the type.
    31  // SmallestNonzero is the smallest positive, non-zero value representable by the type.
    32  const (
    33  	MaxFloat32             = 0x1p127 * (1 + (1 - 0x1p-23)) // 3.40282346638528859811704183484516925440e+38
    34  	SmallestNonzeroFloat32 = 0x1p-126 * 0x1p-23            // 1.401298464324817070923729583289916131280e-45
    35  
    36  	MaxFloat64             = 0x1p1023 * (1 + (1 - 0x1p-52)) // 1.79769313486231570814527423731704356798070e+308
    37  	SmallestNonzeroFloat64 = 0x1p-1022 * 0x1p-52            // 4.9406564584124654417656879286822137236505980e-324
    38  )
    39  
    40  const (
    41  	MaxUintptr = ^uintptr(0)
    42  )
    43  
    44  // Integer limit values.
    45  const (
    46  	intSize = 32 << (^uint(0) >> 63) // 32 or 64
    47  
    48  	MaxInt    = 1<<(intSize-1) - 1  // MaxInt32 or MaxInt64 depending on intSize.
    49  	MinInt    = -1 << (intSize - 1) // MinInt32 or MinInt64 depending on intSize.
    50  	MaxInt8   = 1<<7 - 1            // 127
    51  	MinInt8   = -1 << 7             // -128
    52  	MaxInt16  = 1<<15 - 1           // 32767
    53  	MinInt16  = -1 << 15            // -32768
    54  	MaxInt32  = 1<<31 - 1           // 2147483647
    55  	MinInt32  = -1 << 31            // -2147483648
    56  	MaxInt64  = 1<<63 - 1           // 9223372036854775807
    57  	MinInt64  = -1 << 63            // -9223372036854775808
    58  	MaxUint   = 1<<intSize - 1      // MaxUint32 or MaxUint64 depending on intSize.
    59  	MaxUint8  = 1<<8 - 1            // 255
    60  	MaxUint16 = 1<<16 - 1           // 65535
    61  	MaxUint32 = 1<<32 - 1           // 4294967295
    62  	MaxUint64 = 1<<64 - 1           // 18446744073709551615
    63  )
    64  
    65  const (
    66  	NaN    = 0x7FF8000000000001
    67  	Inf    = 0x7FF0000000000000
    68  	NegInf = 0xFFF0000000000000
    69  )
    70  
    71  // Float32bits returns the IEEE 754 binary representation of f,
    72  // with the sign bit of f and the result in the same bit position.
    73  // Float32bits(Float32frombits(x)) == x.
    74  func Float32bits(f float32) uint32 { return *(*uint32)(unsafe.Pointer(&f)) }
    75  
    76  // Float32frombits returns the floating-point number corresponding
    77  // to the IEEE 754 binary representation b, with the sign bit of b
    78  // and the result in the same bit position.
    79  // Float32frombits(Float32bits(x)) == x.
    80  func Float32frombits(b uint32) float32 { return *(*float32)(unsafe.Pointer(&b)) }
    81  
    82  // Float64bits returns the IEEE 754 binary representation of f,
    83  // with the sign bit of f and the result in the same bit position,
    84  // and Float64bits(Float64frombits(x)) == x.
    85  func Float64bits(f float64) uint64 { return *(*uint64)(unsafe.Pointer(&f)) }
    86  
    87  // Float64frombits returns the floating-point number corresponding
    88  // to the IEEE 754 binary representation b, with the sign bit of b
    89  // and the result in the same bit position.
    90  // Float64frombits(Float64bits(x)) == x.
    91  func Float64frombits(b uint64) float64 { return *(*float64)(unsafe.Pointer(&b)) }