# Changelog for `hspray`

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to the
[Haskell Package Versioning Policy](https://pvp.haskell.org/).


## 0.1.0.0 - 2022-12-11

First release.


## 0.1.1.0 - 2022-12-12

* New functions `toList`, `sprayTerms` and `bombieriSpray`.

* New operation `.^`, to multiply a spray by an integer.

* Added some unit tests.


## 0.1.2.0 - 2023-02-24

New function `derivSpray`, to differentiate a spray.


## 0.1.3.0 - 2023-08-29

* `Powers(..)` is now exported.

* Completed the README to show how to deal with symbolic coefficients.


## 0.2.0.0 - 2024-03-14

* New functions `prettySpray'` and `prettySprayXYZ`.

* New function `substituteSpray`.

* New function `sprayDivision`, to perform the division of a spray by a list of sprays.

* New function `groebner`, to compute a Groebner basis of a list of sprays.

* New function `isSymmetricSpray`, to check whether a spray is a symmetric polynomial.

* New function `isPolynomialOf`, to check whether a spray can be expressed as a polynomial of a given list of sprays.


## 0.2.1.0 - 2024-03-22

* New functions `permuteVariables` and `swapVariables`.

* New function `resultant`, to compute the resultant of two sprays.

* New function `subresultants`, to compute the subresultants of two sprays.


## 0.2.1.1 - 2024-03-25

* Improved the documentation.

* Flipped the order of appearance of the terms in the output of the `prettySpray` functions.


## 0.2.2.0 - 2024-03-26

* Fixed an error in `esPolynomial`, which resulted to a bug in `isSymmetricSpray`.


## 0.2.3.0 - 2024-03-28

* New unit tests.

* Fixed `resultant` and `subresultants`: the variables of the sprays they return were incorrect.

* New function `gcdQX`, to compute the greatest common divisor of two univariate sprays with rational coefficients.


## 0.2.4.0 - 2024-03-30

* Flipped the order of the arguments in `permuteVariables` and `swapVariables`.

* New function `gcdSpray`, to compute the greatest common divisor of two sprays with coefficients in a field. 

* The function `gcdQX` has been removed since `gcdSpray` is more general.

* The function `sprayDivision` has been renamed to `sprayDivisionRemainder`.

* New function `sprayDivision`, returning the quotient and the remainder of the division of two sprays.


## 0.2.5.0 - 2024-04-02

* New function `resultant'` which computes the resultant of two sprays with coefficients in a field. 
Thus it is less general than the function `resultant` but it is more efficient. 

* Fixed a small mistake in `isSymmetricSpray` and `isPolynomialOf`: these functions didn't deal with 
the constant term of the spray.

* New function `psPolynomial` which computes the power sum polynomials.

* A particular type of sprays, namely `SymbolicSpray a`, has been introduced. The coefficients of these 
sprays are ratios of univariate polynomials with `a` coefficients. There is a specialization 
`SymbolicQSpray` for the case when `a` is a type of rational numbers. The necessary instances have 
been defined and there is the function `prettySymbolic(Q)Spray` to display such sprays. There are also 
some functions to perform evaluation of such sprays.