Version=0.2.5 (08/2026)
##fixed
-multiple knots when degree=1 and constraints: inconstistant dividing -> multiplying  by the delta_knots. 0 when  multiple knots  caused error)
##change
-multiply derivative coefficients by h, h^2,h^3 for cubic regression

Version=0.2.4
##change
-update the view basis function
-Update the name of the logical variable in view_basis
-re-organise functions in files
-add vignettes
-add "show" function for polynomial and pp/spline on each interval, base local/canonical

##fixed
-p_norm(x,2) instaed of norm2 for mean square
-print.non_callable_pp


Version=0.2.3 (08/2026)
##changes
- Update README.md with the anouncement of the gui and its docker on github
- Add possibility to chose the type of regression (quantile or mean square)
##fixed
- Case : only 2 knots (1 interval) in 'makpp()' function.
- Length of local polynomial in Bspline_basis in Case  of multiple interior knots
(degenerated case)
-complete contraints with 0 for quartic if missing
- fix extrapolating evalpp if degree=0
- fix confusing name pp_eval (wrong) with evalpp (good) of other R library
Version=0.2.2 (07/2026)

## Bug Fixes
- adapt demos to new notations
- add a new class "bspline_basis" including parameter order_deriv
- derivative of constant polynomials and bsplines,
- bspline_basis, bspline_base_der and bs-direct until order 0

## Changes
- add an option to 'makepp' function to render PP polynomial callable
- add the printable method for the new class "callable_pp"
and "non_callable_pp"
- modify 'makespline' function with a flag the chose callable
or non-callable output


Version=0.2.1 (07/2026)
=============
## Bug Fixes
- Deprecated notation in CVXR
- Small bug preventing the regression when the number of knots is minimal
(only one piece)
- eval_pp : add extroplating values out of the knots range
- Fixed issues with `der3cons` vector lengths for different degrees
- Fixed third derivative constraints for cubic splines
- Complete constraints if not enough are provided if degree=3
- Update `print.callable_spline` method


## Changes
- Updated CVXR syntax, removed deprecated functions and cleaned up code
- Improved solver selection logic with fallback mechanism
- Stabilizing bspline_eval and eval_pp functions for unique interval case
- Allow bspline_eval and eval_pp functions to extrapolate values outside the knots range
- Quantile_spline() :   callable=TRUE is now default value
- New classes as output of quantile_spline: callable_spline and non_callable_spline
- Improved `make_spline` and 'spline_eval' function to handle both list and callable objects



Version=0.2.0 (07/2026)
=============
0) minor updates
- Removed "beta" status
- Added system requirements (Rust/Cargo for Linux) to README
- Updated CRAN badges
1) Concerning knots
- Replaced the variable "knots" by the variable "knot" everywhere to avoid confusion with knots() R build-in function
- changed notation paradigm: variable "knot" refers to knots including ends (replace int_knots in version 1.0.1)
variable "ext_knot" refers to extended knot partition (replace knots in version 1.0.1)
3) Spline Evaluation
-Added case degree=0 which caused problems since some variables (coeff) lose 1 dimension. R automaticaly reduces the dimension of the arrays.
-Rendered the spline container (list of knots, coefficients, degree) callable
-Allowed the call of a spline to pass the spline basis coefficient to accelerate the computations (as well as in the function eval_spline)
4) Add other degree for constrained regression
- quartic splines using Karlin-studen technique for cubic polynomial (monotone) and quadratic polynomial (convex).
- quadratic and linear splines. No major theoretical difficulty.
- Unify all regression functions in a quantile_spline function with selection of the degree as a parameter
