Java等效于Matlab的“eps”或Numpy/Python的“间隔”函数(浮点相对精度)

Background

Matlab's built-in eps function [1] can take a numeric value X and return "the positive distance from abs(X) to the next larger in magnitude floating point number of the same precision".

Matlab的内置eps函数[1]可以取一个数值X，并返回“从abs(X)到下一个更大的浮点数的正距离”。

>> eps(1)
ans =
   2.2204e-16
>> eps(single(1))
ans =
   1.1921e-07
>> eps(1e6)
ans =
   1.1642e-10
>> eps(single(1e6))
ans =
       0.0625

Equivalently, Numpy provides the spacing function [2]:

等效地，Numpy提供了间距函数[2]:

In [18]: import numpy as np

In [19]: np.spacing(1)
Out[19]: 2.2204460492503131e-16

In [20]: np.spacing(np.single(1))
Out[20]: 1.1920929e-07

In [21]: np.spacing(1e6)
Out[21]: 1.1641532182693481e-10

In [22]: np.spacing(np.single(1e6))
Out[22]: 0.0625

Question

Is there an equivalent function in Java (and therefore JVM languages like Clojure)?

在Java中是否有等价的函数(因此JVM语言类似Clojure)?

References

[1] http://www.mathworks.com/help/matlab/ref/eps.html
[1]http://www.mathworks.com/help/matlab/ref/eps.html
[2] Documentation at https://github.com/numpy/numpy/blob/master/numpy/core/code_generators/ufunc_docstrings.py#L2905.
- The actual function implementation in C seems to be at https://github.com/numpy/numpy/blob/master/numpy/core/src/npymath/ieee754.c.src#L323 (the license banner before npy_nextafter gives my question some irony).
- C中实际的功能实现似乎是在https://github.com/numpy/numpy/blob/master/numpy/core/core/npymath/npymath/npymath/npymath/ieee754.c.src #L323 (npy_nextafter之前的许可证横幅给我的问题带来了一些讽刺)。
[2]在https://github.com/numpy/numpy/blob/master/numpy/core/code_generators/ufunc_docstrings.py L2905文档。C中实际的功能实现似乎是在https://github.com/numpy/numpy/blob/master/numpy/core/core/npymath/npymath/npymath/npymath/ieee754.c.src #L323 (npy_nextafter之前的许可证横幅给我的问题带来了一些讽刺)。

1 个解决方案

#1

You want java.lang.math.ulp:

你想要java.lang.math.ulp:

Returns the size of an ulp of the argument. An ulp of a double value is the positive distance between this floating-point value and the double value next larger in magnitude. Note that for non-NaN x, ulp(-x) == ulp(x)

返回参数的ulp大小。一个双值的ulp是这个浮点值与下一个较大的值之间的正距离。注意，对于非nan x, ulp(-x) == ulp(x)

Also, available for floats. Some background on ULPs.

同时,用于浮点数。一些背景就ulp进行。

#1