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math包总结

math包总结

作者: 吃猫的鱼0 | 来源:发表于2018-04-13 16:59 被阅读0次

开发中使用中使用到了math这个包,总结一下math包的主要方法与功能。

func Float32bits

func Float32bits(f float32) uint32

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。

func Float32frombits

func Float32frombits(b uint32) float32

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。

func Float64bits

func Float64bits(f float64) uint64

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。

func Float64frombits

func Float64frombits(b uint64) float64

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。

func Ceil

func Ceil(x float64) float64

返回不小于x的最小整数(的浮点值),特例如下:

Ceil(±0) = ±0
Ceil(±Inf) = ±Inf
Ceil(NaN) = NaN

func Floor

func Floor(x float64) float64

返回不大于x的最小整数(的浮点值),特例如下:

Floor(±0) = ±0
Floor(±Inf) = ±Inf
Floor(NaN) = NaN

func Trunc

func Trunc(x float64) float64

返回x的整数部分(的浮点值)。特例如下:

Trunc(±0) = ±0
Trunc(±Inf) = ±Inf
Trunc(NaN) = NaN

func Modf

func Modf(f float64) (int float64, frac float64)

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:

Modf(±Inf) = ±Inf, NaN
Modf(NaN) = NaN, NaN

func Nextafter

func Nextafter(x, y float64) (r float64)

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:

Nextafter(NaN, y) = NaN
Nextafter(x, NaN) = NaN

func Abs

func Abs(x float64) float64

返回x的绝对值;特例如下:

Abs(±Inf) = +Inf
Abs(NaN) = NaN

func Max

func Max(x, y float64) float64

返回x和y中最大值,特例如下:

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

func Min

func Min(x, y float64) float64

返回x和y中最小值,特例如下:

Min(x, -Inf) = Min(-Inf, x) = -Inf
Min(x, NaN) = Min(NaN, x) = NaN
Min(-0, ±0) = Min(±0, -0) = -0

func Dim

func Dim(x, y float64) float64

函数返回x-y和0中的最大值,特殊情况:

Dim(+Inf, +Inf) = NaN
Dim(-Inf, -Inf) = NaN
Dim(x, NaN) = Dim(NaN, x) = NaN

func Mod

func Mod(x, y float64) float64

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:

Mod(±Inf, y) = NaN
Mod(NaN, y) = NaN
Mod(x, 0) = NaN
Mod(x, ±Inf) = x
Mod(x, NaN) = NaN

func Remainder

func Remainder(x, y float64) float64

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:

Remainder(±Inf, y) = NaN
Remainder(NaN, y) = NaN
Remainder(x, 0) = NaN
Remainder(x, ±Inf) = x
Remainder(x, NaN) = NaN

func Sqrt

func Sqrt(x float64) float64

返回x的二次方根,特例如下:

Sqrt(+Inf) = +Inf
Sqrt(±0) = ±0
Sqrt(x < 0) = NaN
Sqrt(NaN) = NaN

func Cbrt

func Cbrt(x float64) float64

返回x的三次方根,特例如下:

Cbrt(±0) = ±0
Cbrt(±Inf) = ±Inf
Cbrt(NaN) = NaN

func Hypot

func Hypot(p, q float64) float64

返回Sqrt(pp + qq),注意要避免不必要的溢出或下溢。特例如下:

Hypot(±Inf, q) = +Inf
Hypot(p, ±Inf) = +Inf
Hypot(NaN, q) = NaN
Hypot(p, NaN) = NaN

func Sin

func Sin(x float64) float64

求正弦。特例如下:

Sin(±0) = ±0
Sin(±Inf) = NaN
Sin(NaN) = NaN

func Cos

func Cos(x float64) float64

求余弦。特例如下:

Cos(±Inf) = NaN
Cos(NaN) = NaN

func Tan

func Tan(x float64) float64

求正切。特例如下:

Tan(±0) = ±0
Tan(±Inf) = NaN
Tan(NaN) = NaN

func Sincos

func Sincos(x float64) (sin, cos float64)

函数返回Sin(x), Cos(x)。特例如下:

Sincos(±0) = ±0, 1
Sincos(±Inf) = NaN, NaN
Sincos(NaN) = NaN, NaN

func Asin

func Asin(x float64) float64

求反正弦(x是弧度)。特例如下:

Asin(±0) = ±0
Asin(x) = NaN if x < -1 or x > 1

func Acos

func Acos(x float64) float64

求反余弦(x是弧度)。特例如下:

Acos(x) = NaN if x < -1 or x > 1

func Atan

func Atan(x float64) float64

求反正切(x是弧度)。特例如下:

Atan(±0) = ±0
Atan(±Inf) = ±Pi/2

func Atan2

func Atan2(y, x float64) float64

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):

Atan2(y, NaN) = NaN
Atan2(NaN, x) = NaN
Atan2(+0, x>=0) = +0
Atan2(-0, x>=0) = -0
Atan2(+0, x<=-0) = +Pi
Atan2(-0, x<=-0) = -Pi
Atan2(y>0, 0) = +Pi/2
Atan2(y<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>0, -Inf) = +Pi
Atan2(y<0, -Inf) = -Pi
Atan2(+Inf, x) = +Pi/2
Atan2(-Inf, x) = -Pi/2

func Sinh

func Sinh(x float64) float64

求双曲正弦,特例如下:

Sinh(±0) = ±0
Sinh(±Inf) = ±Inf
Sinh(NaN) = NaN

func Cosh

func Cosh(x float64) float64

求双曲余弦,特例如下:

Cosh(±0) = 1
Cosh(±Inf) = +Inf
Cosh(NaN) = NaN

func Tanh

func Tanh(x float64) float64

求双曲正切,特例如下:

Tanh(±0) = ±0
Tanh(±Inf) = ±1
Tanh(NaN) = NaN

func Asinh

func Asinh(x float64) float64

求反双曲正弦,特例如下:

Asinh(±0) = ±0
Asinh(±Inf) = ±Inf
Asinh(NaN) = NaN

func Acosh

func Acosh(x float64) float64

求反双曲余弦,特例如下:

Acosh(+Inf) = +Inf
Acosh(x) = NaN if x < 1
Acosh(NaN) = NaN

func Atanh

func Atanh(x float64) float64

求反双曲正切,特例如下:

Atanh(1) = +Inf
Atanh(±0) = ±0
Atanh(-1) = -Inf
Atanh(x) = NaN if x < -1 or x > 1
Atanh(NaN) = NaN

func Log

func Log(x float64) float64

求自然对数,特例如下:

Log(+Inf) = +Inf
Log(0) = -Inf
Log(x < 0) = NaN
Log(NaN) = NaN

func Log1p

func Log1p(x float64) float64

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:

Log1p(+Inf) = +Inf
Log1p(±0) = ±0
Log1p(-1) = -Inf
Log1p(x < -1) = NaN
Log1p(NaN) = NaN

func Log2

func Log2(x float64) float64

求2为底的对数;特例和Log相同。

func Log10

func Log10(x float64) float64

求10为底的对数;特例和Log相同。

func Logb

func Logb(x float64) float64

返回x的二进制指数值,可以理解为Trunc(Log2(x));特例如下:

Logb(±Inf) = +Inf
Logb(0) = -Inf
Logb(NaN) = NaN

参考:GO标准库中文文档

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