Algebraic Operations on Functions

[marvinpfoertner]

In a Nutshell

This PR implements addition and scalar multiplication on Functions.

This is a proposal for how to redesign all algebraic structures in ProbNum.

Detailed Description

• Function + Function
• ScalarLike * Function
• leverages functools.singledispatchmethod to register the correct result for combinations of different function types

Related Issues

None

[codecov]

Codecov Report

Merging #725 (f73f3a4) into main (e2a46b0) will increase coverage by 0.14%.
The diff coverage is 93.60%.

@@            Coverage Diff             @@
##             main     #725      +/-   ##
==========================================
+ Coverage   90.12%   90.27%   +0.14%     
==========================================
  Files         194      197       +3     
  Lines        7353     7445      +92     
  Branches     1163     1154       -9     
==========================================
+ Hits         6627     6721      +94     
- Misses        486      487       +1     
+ Partials      240      237       -3     

Impacted Files	Coverage Δ
src/probnum/__init__.py	100.00% <ø> (ø)
src/probnum/functions/_zero.py	83.33% <77.77%> (ø)
src/probnum/functions/_algebra_fallbacks.py	88.67% <88.67%> (ø)
src/probnum/functions/__init__.py	100.00% <100.00%> (ø)
src/probnum/functions/_algebra.py	100.00% <100.00%> (ø)
src/probnum/functions/_function.py	96.61% <100.00%> (ø)
src/probnum/randprocs/__init__.py	100.00% <100.00%> (ø)
src/probnum/randprocs/_gaussian_process.py	100.00% <100.00%> (ø)
src/probnum/randprocs/_random_process.py	92.20% <100.00%> (ø)
src/probnum/randprocs/markov/_markov.py	87.50% <100.00%> (ø)
... and 4 more

[JonathanWenger]

Looks great! Just a few clarification questions, but otherwise good to go. Thanks 🙏!