ajdmom.poly

Class Poly, a customized dictionary, derived from UserDict

I defined a new class Poly to extend the UserDict class from the Python Standard Library collections, within which I defined an attribute keyfor and the following magic methods:

Magic Method	Example	Function
__add__()	poly1 + poly2	Addition between two polynomials
__sub__()	poly1 - poly2	Subtraction between two polynomials
__mul__()	poly1 * poly2	Multiplication between two polynomials
__rmul__()	c * poly2	Reversely multiply by a constant
__pow__()	poly ** 2	Raise a polynomial to power n

It should be noted that:

• Addition and subtraction are only for polynomials having the same keyfor attribute.

• The original poly or polys remain unchanged after these operations, all of which return a new poly.

Besides, I defined following methods:

Method	Function
merge()	Merge with another poly having the same keyfor attribute
add_keyval()	Insert a new key-val or add val to the existing key
remove_zero()	Remove any item having value 0
set_keyfor()	Set the keyfor attribute for the poly
mul_poly()	Multiply by another poly of different type and return a new one
is_exact_type()	Check whether the supplied argument is a Poly with the same keyfor
write_to_txt()	Write the poly to a txt file with the keyfor as the title line
write_to_csv()	Write the poly to a csv file with the keyfor as the title line
const_one()	Constant equivalent to 1 in real numbers
const_zero()	Constant equivalent to 0 in real numbers

Note that merge() (in-place) is different from the magic method __add__() (not-in-place). The former changes the original poly, while the latter does not.

Classes

Poly([dict])

Class for different versions of "Polynomial"

Functions

kv(i, key)

get key[i] where key is a tuple