hspray-0.2.6.0: CHANGELOG.md

# 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.


## 0.2.6.0 - 2024-04-15

* New function `collinearSprays` which checks whether two sprays are collinear.

* The function `isPolynomialOf` threw an error when the number of variables in the spray 
to be tested was less than the number of variables in the list of sprays. That is me who 
programmed this error and this was wrong: for example, `x = p1 - p2^*^p3` with `p1 = x + y^*^z`, 
`p2 = y`, and `p3 = z`.

* New functions to print sprays with numeric coefficients, such as `prettyNumSpray` and 
`prettyQSpray`.

* The functions `prettySpray`, `prettySpray'` and `prettySpray''` have been changed.

* New functions to print symbolic sprays.

* Documentation and README have been improved.