Reading the documentation

Ben Bacarisse ben.usenet at bsb.me.uk
Thu Aug 24 21:25:25 EDT 2017


Steve D'Aprano <steve+python at pearwood.info> writes:

> On Fri, 25 Aug 2017 09:41 am, bob gailer wrote:
>
>>> Help on built-in function floor in module math:
>>>
>>> floor(...)
>>>      floor(x)
>>>
>>>      Return the floor of x as an Integral.
>>>      This is the largest integer <= x.
> [...]
>
>> I was surprised by the use of "integral". A dictionary search does not
>> (IMHO) support this usage!
>
> Integral \In"te*gral\, a. [Cf. F. int['e]gral. See Integer.]

For me (and I suspect for BG too) the surprise is in its use as a noun.
The capital letter is, presumably, significant because it refers to the
Python class Integral -- a subtype of numbers.

With that in mind, "an Integral" is a shorthand for "an Integral value",
or more fully, maybe, "an instance of numbers.Integral".

>    [1913 Webster]
>    1. Lacking nothing of completeness; complete; perfect;
>       uninjured; whole; entire.
>       [1913 Webster]
>
>             A local motion keepeth bodies integral. --Bacon.
>       [1913 Webster]
>
>    2. Essential to completeness; constituent, as a part;
>       pertaining to, or serving to form, an integer; integrant.
>       [1913 Webster]
>
>             Ceasing to do evil, and doing good, are the two
>             great integral parts that complete this duty.
>                                                   --South.
>       [1913 Webster]
>
>    3. (Math.)
>       (a) Of, pertaining to, or being, a whole number or
>           undivided quantity; not fractional.
>       (b) Pertaining to, or proceeding by, integration; as, the
>           integral calculus.
>           [1913 Webster]

The use as a noun is not covered here, though it is only a small step
from other places where membership of a mathematical set has turned the
adjective into a noun.  "Rational" and "real" started out as adjectives,
but their use as nouns is now widespread.  "The function returns a
real".  "The result is a rational".  It's much less common for complex
and integral, to the point that it sounds wrong to me.

-- 
Ben.



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