python数学模块Word文档格式.docx

1、is not a float, delegates tox._ceil_（）, which should return anIntegralvalue.math.copysign（x,y）Return a float with the magnitude （absolute value） ofbut the sign ofy. On platforms that support signed zeros,copysign（1.0,-0.0）returns-1.0.math.fabs（x）Return the absolute value ofx.math.factorial（x）Returnf

2、actorial. RaisesValueErrorifis not integral or is negative.math.floor（x）Return the floor ofx, the largest integer less than or equal tois not a float, delegates tox._floor_（）, which should return anmath.fmod（x,fmod（x,y）, as defined by the platform C library. Note that the Python expression%ymay not

3、return the same result. The intent of the C standard is thaty）be exactly （mathematically; to infinite precision） equal to-n*yfor some integernsuch that the result has the same sign asand magnitude less thanabs（y）. Pythonsyreturns a result with the sign ofinstead, and may not be exactly computable fo

4、r float arguments. For example,fmod（-1e-100,1e100）is-1e-100, but the result of Pythons-1e-1001e1001e100-1e-100, which cannot be represented exactly as a float, and rounds to the surprising1e100. For this reason, functionfmod（）is generally preferred when working with floats, while Pythonsis preferred

5、 when working with integers.math.frexp（x）Return the mantissa and exponent ofas the pair（m,e）.mis a float andeis an integer such that=*2*eexactly. Ifis zero, returns（0.0,0）, otherwise0.5=abs（m）sum（.1, .1, .1, .1, .1, .1, .1, .1, .1, .1）0.9999999999999999fsum（.1, .1, .1, .1, .1, .1, .1, .1, .1, .1）1.0

6、The algorithms accuracy depends on IEEE-754 arithmetic guarantees and the typical case where the rounding mode is half-even. On some non-Windows builds, the underlying C library uses extended precision addition and may occasionally double-round an intermediate sum causing it to be off in its least s

7、ignificant bit.For further discussion and two alternative approaches, see theASPN cookbook recipes for accurate floating point summation.math.gcd（a,b）Return the greatest common divisor of the integersaandb. If eitherorbis nonzero, then the value ofgcd（a,b）is the largest positive integer that divides

8、 bothb.gcd（0,0）0.New in version 3.5.math.isclose（a,b,*,rel_tol=1e-09,abs_tol=0.0）Trueif the valuesare close to each other andFalseotherwise.Whether or not two values are considered close is determined according to given absolute and relative tolerances.rel_tolis the relative tolerance it is the maxi

9、mum allowed difference betweenb, relative to the larger absolute value ofb. For example, to set a tolerance of 5%, passrel_tol=0.05. The default tolerance is1e-09, which assures that the two values are the same within about 9 decimal digits.must be greater than zero.abs_tolis the minimum absolute to

10、lerance useful for comparisons near zero.abs_tolmust be at least zero.If no errors occur, the result will be:abs（a-b）max（rel_tolmax（abs（a）,abs（b）,abs_tol）.The IEEE 754 special values ofNaN,inf, and-infwill be handled according to IEEE rules. Specifically,NaNis not considered close to any other value

11、, includingNaN.infare only considered close to themselves.See also：PEP 485 A function for testing approximate equalitymath.isfinite（x）is neither an infinity nor a NaN, andotherwise. （Note that0.0isconsidered finite.）New in version 3.2.math.isinf（x）is a positive or negative infinity, andmath.isnan（x）