mathext

func IsAlmostEqualFloat32 ¶

func IsAlmostEqualFloat32(a, b float32) bool

func IsAlmostEqualFloat64 ¶

func IsAlmostEqualFloat64(a, b float64) bool

Returns true if this number is at most kMaxUlps ULP's away from rhs. In particular, this function:

• returns false if either number is (or both are) NAN.
• treats really large numbers as almost equal to infinity.
• thinks +0.0 and -0.0 are 0 DLP's apart.

func RandFloat ¶

func RandFloat(min, max float64) float64

Random number in [min, max]

func RandInt ¶

func RandInt(min, max int) int

Random integer in [min, max]

func RangePerm ¶

func RangePerm(min, max int) []int

集合内随机取数, [min,max]

func RoundFloat ¶

func RoundFloat(x float64) float64

https://github.com/montanaflynn/stats/blob/master/round.go

func RoundHalf ¶

func RoundHalf(v float64) int

四舍五入

func SignAndMagnitudeToBiasedFloat32 ¶

func SignAndMagnitudeToBiasedFloat32(sam uint32) uint32

func SignAndMagnitudeToBiasedFloat64 ¶

func SignAndMagnitudeToBiasedFloat64(sam uint64) uint64

Converts an integer from the sign-and-magnitude representation to the biased representation. More precisely, let N be 2 to the power of (kBitCount - 1), an integer x is represented by the unsigned number x + N.

For instance,

-N + 1 (the most negative number representable using
       sign-and-magnitude) is represented by 1;
0      is represented by N; and
N - 1  (the biggest number representable using
       sign-and-magnitude) is represented by 2N - 1.

Read http://en.wikipedia.org/wiki/Signed_number_representations for more details on signed number representations.