Skip to content

pow() docs shouldn't require numeric arguments #130102

@skirpichev

Description

@skirpichev

Currently, the second paragraph of docs starts with "The arguments must have numeric types." That seems to be too restrictive and many third-party packages already break this rule. E.g. SymPy support arbitrary symbolic expressions:

In [1]: pow(x, y)
Out[1]: 
 y
x 

In [2]: pow(x, y, z)
Out[2]: 
 y      
x  mod z

Diofant also uses both forms for polynomial arithmetic:

In [1]: R, x = ring('x', QQ)

In [2]: pow(x + 1, 7, 2*x**2 - 1)
Out[2]: 239/8*x + 169/8

In [3]: ((x + 1)**7) % (2*x**2 - 1)
Out[3]: 239/8*x + 169/8

In [4]: (x + 1)**2
Out[4]: x**2 + 2*x + 1

In [5]: pow(x + 1, 2)
Out[5]: x**2 + 2*x + 1

I suggest to drop this requirement. In fact, first paragraph already mention equivalents for two-arg and three-arg versions of the pow(). We can rephrase it like this: "Return base to the power exp, an equivalent to base**exp; if mod is present, return base to the power exp, modulo mod, an equivalent to (base**exp) % mod (but computed more efficiently)."

The third paragraph also might instead specify requirements for the mod in case of integer base and exponent, not just for builtin int's.

Linked PRs

Metadata

Metadata

Assignees

No one assigned

    Labels

    docsDocumentation in the Doc dir

    Projects

    Status

    Todo

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions