uTools-Manuals/src/docs/go/math.html

<div class="container">
    <h1 id="pkg-overview">package math</h1>
    <p><code>import "math"</code>
    </p><p>math包提供了基本的数学常数和数学函数。</p>
    
    
		
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
    
    <h2 id="pkg-constants">Constants </h2>
    <pre>const (
    <span id="E">E</span>   = 2.71828182845904523536028747135266249775724709369995957496696763 <span class="com">// A001113</span>
    <span id="Pi">Pi</span>  = 3.14159265358979323846264338327950288419716939937510582097494459 <span class="com">// A000796</span>
    <span id="Phi">Phi</span> = 1.61803398874989484820458683436563811772030917980576286213544862 <span class="com">// A001622</span>
    <span id="Sqrt2">Sqrt2</span>   = 1.41421356237309504880168872420969807856967187537694807317667974 <span class="com">// A002193</span>
    <span id="SqrtE">SqrtE</span>   = 1.64872127070012814684865078781416357165377610071014801157507931 <span class="com">// A019774</span>
    <span id="SqrtPi">SqrtPi</span>  = 1.77245385090551602729816748334114518279754945612238712821380779 <span class="com">// A002161</span>
    <span id="SqrtPhi">SqrtPhi</span> = 1.27201964951406896425242246173749149171560804184009624861664038 <span class="com">// A139339</span>
    <span id="Ln2">Ln2</span>    = 0.693147180559945309417232121458176568075500134360255254120680009 <span class="com">// A002162</span>
    <span id="Log2E">Log2E</span>  = 1 / <a href="#Ln2">Ln2</a>
    <span id="Ln10">Ln10</span>   = 2.30258509299404568401799145468436420760110148862877297603332790 <span class="com">// A002392</span>
    <span id="Log10E">Log10E</span> = 1 / <a href="#Ln10">Ln10</a>
)</pre>
    <p>数学常数，参见：<a href="http://oeis.org/Axxxxxx">http://oeis.org/Axxxxxx</a></p>
    <pre>const (
    <span id="MaxFloat32">MaxFloat32</span>             = 3.40282346638528859811704183484516925440e+38  <span class="com">// 2**127 * (2**24 - 1) / 2**23</span>
    <span id="SmallestNonzeroFloat32">SmallestNonzeroFloat32</span> = 1.401298464324817070923729583289916131280e-45 <span class="com">// 1 / 2**(127 - 1 + 23)</span>
    <span id="MaxFloat64">MaxFloat64</span>             = 1.797693134862315708145274237317043567981e+308 <span class="com">// 2**1023 * (2**53 - 1) / 2**52</span>
    <span id="SmallestNonzeroFloat64">SmallestNonzeroFloat64</span> = 4.940656458412465441765687928682213723651e-324 <span class="com">// 1 / 2**(1023 - 1 + 52)</span>
)</pre>
    <p>浮点数的取值极限。Max是该类型所能表示的最大有限值；SmallestNonzero是该类型所能表示的最小非零正数值。</p>
    <pre>const (
    <span id="MaxInt8">MaxInt8</span>   = 1&lt;&lt;7 - 1
    <span id="MinInt8">MinInt8</span>   = -1 &lt;&lt; 7
    <span id="MaxInt16">MaxInt16</span>  = 1&lt;&lt;15 - 1
    <span id="MinInt16">MinInt16</span>  = -1 &lt;&lt; 15
    <span id="MaxInt32">MaxInt32</span>  = 1&lt;&lt;31 - 1
    <span id="MinInt32">MinInt32</span>  = -1 &lt;&lt; 31
    <span id="MaxInt64">MaxInt64</span>  = 1&lt;&lt;63 - 1
    <span id="MinInt64">MinInt64</span>  = -1 &lt;&lt; 63
    <span id="MaxUint8">MaxUint8</span>  = 1&lt;&lt;8 - 1
    <span id="MaxUint16">MaxUint16</span> = 1&lt;&lt;16 - 1
    <span id="MaxUint32">MaxUint32</span> = 1&lt;&lt;32 - 1
    <span id="MaxUint64">MaxUint64</span> = 1&lt;&lt;64 - 1
)</pre>
    <p>整数的取值极限。</p>
    <h2 id="NaN">func <a href="https://github.com/golang/go/blob/master/src/math/bits.go?name=release#28" title="View Source">NaN</a> </h2>
    <pre class="funcdecl">func NaN() <a href="builtin.htm#float64">float64</a></pre>
    <p>函数返回一个IEEE 754“这不是一个数字”值。</p>
    <h2 id="IsNaN">func <a href="https://github.com/golang/go/blob/master/src/math/bits.go?name=release#31" title="View Source">IsNaN</a> </h2>
    <pre class="funcdecl">func IsNaN(f <a href="builtin.htm#float64">float64</a>) (is <a href="builtin.htm#bool">bool</a>)</pre>
    <p>报告f是否表示一个NaN（Not A Number）值。</p>
    <h2 id="Inf">func <a href="https://github.com/golang/go/blob/master/src/math/bits.go?name=release#17" title="View Source">Inf</a> </h2>
    <pre class="funcdecl">func Inf(sign <a href="builtin.htm#int">int</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>如果sign&gt;=0函数返回正无穷大，否则返回负无穷大。</p>
    <h2 id="IsInf">func <a href="https://github.com/golang/go/blob/master/src/math/bits.go?name=release#43" title="View Source">IsInf</a> </h2>
    <pre class="funcdecl">func IsInf(f <a href="builtin.htm#float64">float64</a>, sign <a href="builtin.htm#int">int</a>) <a href="builtin.htm#bool">bool</a></pre>
    <p>如果sign &gt; 0，f是正无穷大时返回真；如果sign&lt;0，f是负无穷大时返回真；sign==0则f是两种无穷大时都返回真。</p>
    <h2 id="Float32bits">func <a href="https://github.com/golang/go/blob/master/src/math/unsafe.go?name=release#10" title="View Source">Float32bits</a> </h2>
    <pre class="funcdecl">func Float32bits(f <a href="builtin.htm#float32">float32</a>) <a href="builtin.htm#uint32">uint32</a></pre>
    <p>函数返回浮点数f的IEEE 754格式二进制表示对应的4字节无符号整数。</p>
    <h2 id="Float32frombits">func <a href="https://github.com/golang/go/blob/master/src/math/unsafe.go?name=release#14" title="View Source">Float32frombits</a> </h2>
    <pre class="funcdecl">func Float32frombits(b <a href="builtin.htm#uint32">uint32</a>) <a href="builtin.htm#float32">float32</a></pre>
    <p>函数返回无符号整数b对应的IEEE 754格式二进制表示的4字节浮点数。</p>
    <h2 id="Float64bits">func <a href="https://github.com/golang/go/blob/master/src/math/unsafe.go?name=release#17" title="View Source">Float64bits</a> </h2>
    <pre class="funcdecl">func Float64bits(f <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#uint64">uint64</a></pre>
    <p>函数返回浮点数f的IEEE 754格式二进制表示对应的8字节无符号整数。</p>
    <h2 id="Float64frombits">func <a href="https://github.com/golang/go/blob/master/src/math/unsafe.go?name=release#21" title="View Source">Float64frombits</a> </h2>
    <pre class="funcdecl">func Float64frombits(b <a href="builtin.htm#uint64">uint64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>函数返回无符号整数b对应的IEEE 754格式二进制表示的8字节浮点数。</p>
    <h2 id="Signbit">func <a href="https://github.com/golang/go/blob/master/src/math/signbit.go?name=release#8" title="View Source">Signbit</a> </h2>
    <pre class="funcdecl">func Signbit(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#bool">bool</a></pre>
    <p>如果x是一个负数或者负零，返回真。</p>
    <h2 id="Copysign">func <a href="https://github.com/golang/go/blob/master/src/math/copysign.go?name=release#9" title="View Source">Copysign</a> </h2>
    <pre class="funcdecl">func Copysign(x, y <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回拥有x的量值（绝对值）和y的标志位（正负号）的浮点数。</p>
    <h2 id="Ceil">func <a href="https://github.com/golang/go/blob/master/src/math/floor.go?name=release#36" title="View Source">Ceil</a> </h2>
    <pre class="funcdecl">func Ceil(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回不小于x的最小整数（的浮点值），特例如下：</p>
    <pre>Ceil(±0) = ±0
Ceil(±Inf) = ±Inf
Ceil(NaN) = NaN</pre>
    <h2 id="Floor">func <a href="https://github.com/golang/go/blob/master/src/math/floor.go?name=release#13" title="View Source">Floor</a> </h2>
    <pre class="funcdecl">func Floor(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回不大于x的最大整数（的浮点值），特例如下：</p>
    <pre>Floor(±0) = ±0
Floor(±Inf) = ±Inf
Floor(NaN) = NaN</pre>
    <h2 id="Trunc">func <a href="https://github.com/golang/go/blob/master/src/math/floor.go?name=release#48" title="View Source">Trunc</a> </h2>
    <pre class="funcdecl">func Trunc(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回x的整数部分（的浮点值）。特例如下：</p>
    <pre>Trunc(±0) = ±0
Trunc(±Inf) = ±Inf
Trunc(NaN) = NaN</pre>
    <h2 id="Modf">func <a href="https://github.com/golang/go/blob/master/src/math/modf.go?name=release#13" title="View Source">Modf</a> </h2>
    <pre class="funcdecl">func Modf(f <a href="builtin.htm#float64">float64</a>) (int <a href="builtin.htm#float64">float64</a>, frac <a href="builtin.htm#float64">float64</a>)</pre>
    <p>返回f的整数部分和小数部分，结果的正负号和都x相同；特例如下：</p>
    <pre>Modf(±Inf) = ±Inf, NaN
Modf(NaN) = NaN, NaN</pre>
    <h2 id="Nextafter">func <a href="https://github.com/golang/go/blob/master/src/math/nextafter.go?name=release#13" title="View Source">Nextafter</a> </h2>
    <pre class="funcdecl">func Nextafter(x, y <a href="builtin.htm#float64">float64</a>) (r <a href="builtin.htm#float64">float64</a>)</pre>
    <p>参数x到参数y的方向上，下一个可表示的数值；如果x==y将返回x。特例如下：</p>
    <pre>Nextafter(NaN, y) = NaN
Nextafter(x, NaN) = NaN</pre>
    <h2 id="Abs">func <a href="https://github.com/golang/go/blob/master/src/math/abs.go?name=release#12" title="View Source">Abs</a> </h2>
    <pre class="funcdecl">func Abs(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回x的绝对值；特例如下：</p>
    <pre>Abs(±Inf) = +Inf
Abs(NaN) = NaN</pre>
    <h2 id="Max">func <a href="https://github.com/golang/go/blob/master/src/math/dim.go?name=release#26" title="View Source">Max</a> </h2>
    <pre class="funcdecl">func Max(x, y <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回x和y中最大值，特例如下：</p>
    <pre>Max(x, +Inf) = Max(+Inf, x) = +Inf
Max(x, NaN) = Max(NaN, x) = NaN
Max(+0, ±0) = Max(±0, +0) = +0
Max(-0, -0) = -0</pre>
    <h2 id="Min">func <a href="https://github.com/golang/go/blob/master/src/math/dim.go?name=release#53" title="View Source">Min</a> </h2>
    <pre class="funcdecl">func Min(x, y <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回x和y中最小值，特例如下：</p>
    <pre>Min(x, -Inf) = Min(-Inf, x) = -Inf
Min(x, NaN) = Min(NaN, x) = NaN
Min(-0, ±0) = Min(±0, -0) = -0</pre>
    <h2 id="Dim">func <a href="https://github.com/golang/go/blob/master/src/math/dim.go?name=release#13" title="View Source">Dim</a> </h2>
    <pre class="funcdecl">func Dim(x, y <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>函数返回x-y和0中的最大值，特殊情况：</p>
    <pre>Dim(+Inf, +Inf) = NaN
Dim(-Inf, -Inf) = NaN
Dim(x, NaN) = Dim(NaN, x) = NaN</pre>
    <h2 id="Mod">func <a href="https://github.com/golang/go/blob/master/src/math/mod.go?name=release#21" title="View Source">Mod</a> </h2>
    <pre class="funcdecl">func Mod(x, y <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>取余运算，可以理解为 x-Trunc(x/y)*y，结果的正负号和x相同；特例如下：</p>
    <pre>Mod(±Inf, y) = NaN
Mod(NaN, y) = NaN
Mod(x, 0) = NaN
Mod(x, ±Inf) = x
Mod(x, NaN) = NaN</pre>
    <h2 id="Remainder">func <a href="https://github.com/golang/go/blob/master/src/math/remainder.go?name=release#37" title="View Source">Remainder</a> </h2>
    <pre class="funcdecl">func Remainder(x, y <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>IEEE 754差数求值，即x减去最接近x/y的整数值（如果有两个整数与x/y距离相同，则取其中的偶数）与y的乘积。特例如下：</p>
    <pre>Remainder(±Inf, y) = NaN
Remainder(NaN, y) = NaN
Remainder(x, 0) = NaN
Remainder(x, ±Inf) = x
Remainder(x, NaN) = NaN</pre>
    <h2 id="Sqrt">func <a href="https://github.com/golang/go/blob/master/src/math/sqrt.go?name=release#92" title="View Source">Sqrt</a> </h2>
    <pre class="funcdecl">func Sqrt(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回x的二次方根，特例如下：</p>
    <pre>Sqrt(+Inf) = +Inf
Sqrt(±0) = ±0
Sqrt(x &lt; 0) = NaN
Sqrt(NaN) = NaN</pre>
    <h2 id="Cbrt">func <a href="https://github.com/golang/go/blob/master/src/math/cbrt.go?name=release#21" title="View Source">Cbrt</a> </h2>
    <pre class="funcdecl">func Cbrt(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回x的三次方根，特例如下：</p>
    <pre>Cbrt(±0) = ±0
Cbrt(±Inf) = ±Inf
Cbrt(NaN) = NaN</pre>
    <h2 id="Hypot">func <a href="https://github.com/golang/go/blob/master/src/math/hypot.go?name=release#19" title="View Source">Hypot</a> </h2>
    <pre class="funcdecl">func Hypot(p, q <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回Sqrt(p*p + q*q)，注意要避免不必要的溢出或下溢。特例如下：</p>
    <pre>Hypot(±Inf, q) = +Inf
Hypot(p, ±Inf) = +Inf
Hypot(NaN, q) = NaN
Hypot(p, NaN) = NaN</pre>
    <h2 id="Sin">func <a href="https://github.com/golang/go/blob/master/src/math/sin.go?name=release#174" title="View Source">Sin</a> </h2>
    <pre class="funcdecl">func Sin(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求正弦。特例如下：</p>
    <pre>Sin(±0) = ±0
Sin(±Inf) = NaN
Sin(NaN) = NaN</pre>
    <h2 id="Cos">func <a href="https://github.com/golang/go/blob/master/src/math/sin.go?name=release#117" title="View Source">Cos</a> </h2>
    <pre class="funcdecl">func Cos(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求余弦。特例如下：</p>
    <pre>Cos(±Inf) = NaN
Cos(NaN) = NaN</pre>
    <h2 id="Tan">func <a href="https://github.com/golang/go/blob/master/src/math/tan.go?name=release#82" title="View Source">Tan</a> </h2>
    <pre class="funcdecl">func Tan(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求正切。特例如下：</p>
    <pre>Tan(±0) = ±0
Tan(±Inf) = NaN
Tan(NaN) = NaN</pre>
    <h2 id="Sincos">func <a href="https://github.com/golang/go/blob/master/src/math/sincos.go?name=release#15" title="View Source">Sincos</a> </h2>
    <pre class="funcdecl">func Sincos(x <a href="builtin.htm#float64">float64</a>) (sin, cos <a href="builtin.htm#float64">float64</a>)</pre>
    <p>函数返回Sin(x), Cos(x)。特例如下：</p>
    <pre>Sincos(±0) = ±0, 1
Sincos(±Inf) = NaN, NaN
Sincos(NaN) = NaN, NaN</pre>
    <h2 id="Asin">func <a href="https://github.com/golang/go/blob/master/src/math/asin.go?name=release#19" title="View Source">Asin</a> </h2>
    <pre class="funcdecl">func Asin(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求反正弦（x是弧度）。特例如下：</p>
    <pre>Asin(±0) = ±0
Asin(x) = NaN if x &lt; -1 or x &gt; 1
</pre>
    <h2 id="Acos">func <a href="https://github.com/golang/go/blob/master/src/math/asin.go?name=release#51" title="View Source">Acos</a> </h2>
    <pre class="funcdecl">func Acos(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求反余弦（x是弧度）。特例如下：</p>
    <pre>Acos(x) = NaN if x &lt; -1 or x &gt; 1
</pre>
    <h2 id="Atan">func <a href="https://github.com/golang/go/blob/master/src/math/atan.go?name=release#95" title="View Source">Atan</a> </h2>
    <pre class="funcdecl">func Atan(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求反正切（x是弧度）。特例如下：</p>
    <pre>Atan(±0) = ±0
Atan(±Inf) = ±Pi/2</pre>
    <h2 id="Atan2">func <a href="https://github.com/golang/go/blob/master/src/math/atan2.go?name=release#29" title="View Source">Atan2</a> </h2>
    <pre class="funcdecl">func Atan2(y, x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>类似Atan(y/x)，但会根据x，y的正负号确定象限。特例如下（前面的优先）：</p>
    <pre>Atan2(y, NaN) = NaN
Atan2(NaN, x) = NaN
Atan2(+0, x&gt;=0) = +0
Atan2(-0, x&gt;=0) = -0
Atan2(+0, x&lt;=-0) = +Pi
Atan2(-0, x&lt;=-0) = -Pi
Atan2(y&gt;0, 0) = +Pi/2
Atan2(y&lt;0, 0) = -Pi/2
Atan2(+Inf, +Inf) = +Pi/4
Atan2(-Inf, +Inf) = -Pi/4
Atan2(+Inf, -Inf) = 3Pi/4
Atan2(-Inf, -Inf) = -3Pi/4
Atan2(y, +Inf) = 0
Atan2(y&gt;0, -Inf) = +Pi
Atan2(y&lt;0, -Inf) = -Pi
Atan2(+Inf, x) = +Pi/2
Atan2(-Inf, x) = -Pi/2</pre>
    <h2 id="Sinh">func <a href="https://github.com/golang/go/blob/master/src/math/sinh.go?name=release#25" title="View Source">Sinh</a> </h2>
    <pre class="funcdecl">func Sinh(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求双曲正弦，特例如下：</p>
    <pre>Sinh(±0) = ±0
Sinh(±Inf) = ±Inf
Sinh(NaN) = NaN</pre>
    <h2 id="Cosh">func <a href="https://github.com/golang/go/blob/master/src/math/sinh.go?name=release#69" title="View Source">Cosh</a> </h2>
    <pre class="funcdecl">func Cosh(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求双曲余弦，特例如下：</p>
    <pre>Cosh(±0) = 1
Cosh(±Inf) = +Inf
Cosh(NaN) = NaN</pre>
    <h2 id="Tanh">func <a href="https://github.com/golang/go/blob/master/src/math/tanh.go?name=release#74" title="View Source">Tanh</a> </h2>
    <pre class="funcdecl">func Tanh(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求双曲正切，特例如下：</p>
    <pre>Tanh(±0) = ±0
Tanh(±Inf) = ±1
Tanh(NaN) = NaN</pre>
    <h2 id="Asinh">func <a href="https://github.com/golang/go/blob/master/src/math/asinh.go?name=release#39" title="View Source">Asinh</a> </h2>
    <pre class="funcdecl">func Asinh(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求反双曲正弦，特例如下：</p>
    <pre>Asinh(±0) = ±0
Asinh(±Inf) = ±Inf
Asinh(NaN) = NaN</pre>
    <h2 id="Acosh">func <a href="https://github.com/golang/go/blob/master/src/math/acosh.go?name=release#42" title="View Source">Acosh</a> </h2>
    <pre class="funcdecl">func Acosh(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求反双曲余弦，特例如下：</p>
    <pre>Acosh(+Inf) = +Inf
Acosh(x) = NaN if x &lt; 1
Acosh(NaN) = NaN</pre>
    <h2 id="Atanh">func <a href="https://github.com/golang/go/blob/master/src/math/atanh.go?name=release#47" title="View Source">Atanh</a> </h2>
    <pre class="funcdecl">func Atanh(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求反双曲正切，特例如下：</p>
    <pre>Atanh(1) = +Inf
Atanh(±0) = ±0
Atanh(-1) = -Inf
Atanh(x) = NaN if x &lt; -1 or x &gt; 1
Atanh(NaN) = NaN</pre>
    <h2 id="Log">func <a href="https://github.com/golang/go/blob/master/src/math/log.go?name=release#80" title="View Source">Log</a> </h2>
    <pre class="funcdecl">func Log(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求自然对数，特例如下：</p>
    <pre>Log(+Inf) = +Inf
Log(0) = -Inf
Log(x &lt; 0) = NaN
Log(NaN) = NaN</pre>
    <h2 id="Log1p">func <a href="https://github.com/golang/go/blob/master/src/math/log1p.go?name=release#95" title="View Source">Log1p</a> </h2>
    <pre class="funcdecl">func Log1p(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>等价于Log(1+x)。但是在x接近0时，本函数更加精确；特例如下：</p>
    <pre>Log1p(+Inf) = +Inf
Log1p(±0) = ±0
Log1p(-1) = -Inf
Log1p(x &lt; -1) = NaN
Log1p(NaN) = NaN</pre>
    <h2 id="Log2">func <a href="https://github.com/golang/go/blob/master/src/math/log10.go?name=release#17" title="View Source">Log2</a> </h2>
    <pre class="funcdecl">func Log2(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求2为底的对数；特例和Log相同。</p>
    <h2 id="Log10">func <a href="https://github.com/golang/go/blob/master/src/math/log10.go?name=release#9" title="View Source">Log10</a> </h2>
    <pre class="funcdecl">func Log10(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>求10为底的对数；特例和Log相同。</p>
    <h2 id="Logb">func <a href="https://github.com/golang/go/blob/master/src/math/logb.go?name=release#13" title="View Source">Logb</a> </h2>
    <pre class="funcdecl">func Logb(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回x的二进制指数值，可以理解为Trunc(Log2(x))；特例如下：</p>
    <pre>Logb(±Inf) = +Inf
Logb(0) = -Inf
Logb(NaN) = NaN</pre>
    <h2 id="Ilogb">func <a href="https://github.com/golang/go/blob/master/src/math/logb.go?name=release#32" title="View Source">Ilogb</a> </h2>
    <pre class="funcdecl">func Ilogb(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#int">int</a></pre>
    <p>类似Logb，但返回值是整型；特例如下：</p>
    <pre>Ilogb(±Inf) = MaxInt32
Ilogb(0) = MinInt32
Ilogb(NaN) = MaxInt32</pre>
    <h2 id="Frexp">func <a href="https://github.com/golang/go/blob/master/src/math/frexp.go?name=release#16" title="View Source">Frexp</a> </h2>
    <pre class="funcdecl">func Frexp(f <a href="builtin.htm#float64">float64</a>) (frac <a href="builtin.htm#float64">float64</a>, exp <a href="builtin.htm#int">int</a>)</pre>
    <p>返回一个标准化小数frac和2的整型指数exp，满足f == frac * 2**exp，且0.5 &lt;= Abs(frac) &lt; 1；特例如下：</p>
    <pre>Frexp(±0) = ±0, 0
Frexp(±Inf) = ±Inf, 0
Frexp(NaN) = NaN, 0</pre>
    <h2 id="Ldexp">func <a href="https://github.com/golang/go/blob/master/src/math/ldexp.go?name=release#14" title="View Source">Ldexp</a> </h2>
    <pre class="funcdecl">func Ldexp(frac <a href="builtin.htm#float64">float64</a>, exp <a href="builtin.htm#int">int</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>Frexp的反函数，返回 frac * 2**exp。特例如下：</p>
    <pre>Ldexp(±0, exp) = ±0
Ldexp(±Inf, exp) = ±Inf
Ldexp(NaN, exp) = NaN</pre>
    <h2 id="Exp">func <a href="https://github.com/golang/go/blob/master/src/math/exp.go?name=release#14" title="View Source">Exp</a> </h2>
    <pre class="funcdecl">func Exp(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回E**x；x绝对值很大时可能会溢出为0或者+Inf，x绝对值很小时可能会下溢为1。特例如下：</p>
    <pre>Exp(+Inf) = +Inf
Exp(NaN) = NaN</pre>
    <h2 id="Expm1">func <a href="https://github.com/golang/go/blob/master/src/math/expm1.go?name=release#124" title="View Source">Expm1</a> </h2>
    <pre class="funcdecl">func Expm1(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>等价于Exp(x)-1，但是在x接近零时更精确；x绝对值很大时可能会溢出为-1或+Inf。特例如下：</p>
    <pre>Expm1(+Inf) = +Inf
Expm1(-Inf) = -1
Expm1(NaN) = NaN</pre>
    <h2 id="Exp2">func <a href="https://github.com/golang/go/blob/master/src/math/exp.go?name=release#135" title="View Source">Exp2</a> </h2>
    <pre class="funcdecl">func Exp2(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回2**x；特例和Exp相同。</p>
    <h2 id="Pow">func <a href="https://github.com/golang/go/blob/master/src/math/pow.go?name=release#38" title="View Source">Pow</a> </h2>
    <pre class="funcdecl">func Pow(x, y <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回x**y；特例如下（前面的优先）：</p>
    <pre>Pow(x, ±0) = 1 for any x
Pow(1, y) = 1 for any y
Pow(x, 1) = x for any x
Pow(NaN, y) = NaN
Pow(x, NaN) = NaN
Pow(±0, y) = ±Inf for y an odd integer &lt; 0
Pow(±0, -Inf) = +Inf
Pow(±0, +Inf) = +0
Pow(±0, y) = +Inf for finite y &lt; 0 and not an odd integer
Pow(±0, y) = ±0 for y an odd integer &gt; 0
Pow(±0, y) = +0 for finite y &gt; 0 and not an odd integer
Pow(-1, ±Inf) = 1
Pow(x, +Inf) = +Inf for |x| &gt; 1
Pow(x, -Inf) = +0 for |x| &gt; 1
Pow(x, +Inf) = +0 for |x| &lt; 1
Pow(x, -Inf) = +Inf for |x| &lt; 1
Pow(+Inf, y) = +Inf for y &gt; 0
Pow(+Inf, y) = +0 for y &lt; 0
Pow(-Inf, y) = Pow(-0, -y)
Pow(x, y) = NaN for finite x &lt; 0 and finite non-integer y
</pre>
    <h2 id="Pow10">func <a href="https://github.com/golang/go/blob/master/src/math/pow10.go?name=release#16" title="View Source">Pow10</a> </h2>
    <pre class="funcdecl">func Pow10(e <a href="builtin.htm#int">int</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>返回10**e；特例如下：</p>
    <pre>Pow10(e) = +Inf for e &gt; 309
Pow10(e) = 0 for e &lt; -324
</pre>
    <h2 id="Gamma">func <a href="https://github.com/golang/go/blob/master/src/math/gamma.go?name=release#122" title="View Source">Gamma</a> </h2>
    <pre class="funcdecl">func Gamma(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>伽玛函数（当x为正整数时，值为(x-1)!）。特例如下：</p>
    <pre>Gamma(+Inf) = +Inf
Gamma(+0) = +Inf
Gamma(-0) = -Inf
Gamma(x) = NaN for integer x &lt; 0
Gamma(-Inf) = NaN
Gamma(NaN) = NaN</pre>
    <h2 id="Lgamma">func <a href="https://github.com/golang/go/blob/master/src/math/lgamma.go?name=release#174" title="View Source">Lgamma</a> </h2>
    <pre class="funcdecl">func Lgamma(x <a href="builtin.htm#float64">float64</a>) (lgamma <a href="builtin.htm#float64">float64</a>, sign <a href="builtin.htm#int">int</a>)</pre>
    <p>返回Gamma(x)的自然对数和正负号。特例如下：</p>
    <pre>Lgamma(+Inf) = +Inf
Lgamma(0) = +Inf
Lgamma(-integer) = +Inf
Lgamma(-Inf) = -Inf
Lgamma(NaN) = NaN</pre>
    <h2 id="Erf">func <a href="https://github.com/golang/go/blob/master/src/math/erf.go?name=release#188" title="View Source">Erf</a> </h2>
    <pre class="funcdecl">func Erf(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>误差函数，特例如下：</p>
    <pre>Erf(+Inf) = 1
Erf(-Inf) = -1
Erf(NaN) = NaN</pre>
    <h2 id="Erfc">func <a href="https://github.com/golang/go/blob/master/src/math/erf.go?name=release#265" title="View Source">Erfc</a> </h2>
    <pre class="funcdecl">func Erfc(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>余补误差函数，特例如下：</p>
    <pre>Erfc(+Inf) = 0
Erfc(-Inf) = 2
Erfc(NaN) = NaN</pre>
    <h2 id="J0">func <a href="https://github.com/golang/go/blob/master/src/math/j0.go?name=release#76" title="View Source">J0</a> </h2>
    <pre class="funcdecl">func J0(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>第一类贝塞尔函数，0阶。特例如下：</p>
    <pre>J0(±Inf) = 0
J0(0) = 1
J0(NaN) = NaN</pre>
    <h2 id="J1">func <a href="https://github.com/golang/go/blob/master/src/math/j1.go?name=release#74" title="View Source">J1</a> </h2>
    <pre class="funcdecl">func J1(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>第一类贝塞尔函数，1阶。特例如下：</p>
    <pre>J1(±Inf) = 0
J1(NaN) = NaN</pre>
    <h2 id="Jn">func <a href="https://github.com/golang/go/blob/master/src/math/jn.go?name=release#53" title="View Source">Jn</a> </h2>
    <pre class="funcdecl">func Jn(n <a href="builtin.htm#int">int</a>, x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>第一类贝塞尔函数，n阶。特例如下：</p>
    <pre>Jn(n, ±Inf) = 0
Jn(n, NaN) = NaN</pre>
    <h2 id="Y0">func <a href="https://github.com/golang/go/blob/master/src/math/j0.go?name=release#156" title="View Source">Y0</a> </h2>
    <pre class="funcdecl">func Y0(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>第二类贝塞尔函数，0阶。特例如下：</p>
    <pre>Y0(+Inf) = 0
Y0(0) = -Inf
Y0(x &lt; 0) = NaN
Y0(NaN) = NaN</pre>
    <h2 id="Y1">func <a href="https://github.com/golang/go/blob/master/src/math/j1.go?name=release#154" title="View Source">Y1</a> </h2>
    <pre class="funcdecl">func Y1(x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>第二类贝塞尔函数，1阶。特例如下：</p>
    <pre>Y1(+Inf) = 0
Y1(0) = -Inf
Y1(x &lt; 0) = NaN
Y1(NaN) = NaN</pre>
    <h2 id="Yn">func <a href="https://github.com/golang/go/blob/master/src/math/jn.go?name=release#235" title="View Source">Yn</a> </h2>
    <pre class="funcdecl">func Yn(n <a href="builtin.htm#int">int</a>, x <a href="builtin.htm#float64">float64</a>) <a href="builtin.htm#float64">float64</a></pre>
    <p>第二类贝塞尔函数，n阶。特例如下：</p>
    <pre>Yn(n, +Inf) = 0
Yn(n &gt; 0, 0) = -Inf
Yn(n &lt; 0, 0) = +Inf if n is odd, -Inf if n is even
Y1(n, x &lt; 0) = NaN
Y1(n, NaN) = NaN</pre>
</div>