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如何检查平线浮体的大小?
原标题:How to check the size of a float in python?
  • 时间:2011-11-21 17:43:45
  •  标签:
  • python
  • numpy

我要检查的是,浮标是否实际上为32或64比特(以及平价浮动阵列的借方数目)。 应当有一个内在的方面,但只是找到了。

最佳回答

可在sys.float_info查询。 它收集了诸如最高/最高价值、最高/权宜等信息。 这些特性有可能被用于计算浮体的沥滤面积。 我从未遇到过64条轨道以外的任何东西,但在许多不同的结构中。

The items of a NumPy array might have different size, but you can check their size in bytes by a.itemsize, where a is a NumPy array.

问题回答

numpy.finfo lists sizes and other attributes of float32 ..., including
nexp : number of bits in the exponent including its sign and bias.
nmant : number of bits in the mantissa.
On a machine with IEEE-754 standard floating point,

import numpy as np
for f in (np.float32, np.float64, float):
    finfo = np.finfo(f)
    print finfo.dtype, finfo.nexp, finfo.nmant

will print e.g.

float32 8 23
float64 11 52
float64 11 52

(Tryrot16和浮128)

print numpy.finfo(numpy.float)
Machine parameters for float64
---------------------------------------------------------------------
precision= 15   resolution= 1.0000000000000001e-15
machep=   -52   eps=        2.2204460492503131e-16
negep =   -53   epsneg=     1.1102230246251565e-16   
minexp= -1022   tiny=       2.2250738585072014e-308
maxexp=  1024   max=        1.7976931348623157e+308
nexp  =    11   min=        -max
---------------------------------------------------------------------

python -c "import sys,math; print(sys.float_info.mant_dig + math.ceil(math.log2(sys.float_info.max_10_exp - sys.float_info.min_10_exp)) + 1)"

“+1”是因为在红特萨储存一名数字是含蓄的。





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