Add AdjustableMultiFidelityFunction class

[sjvrijn]

• [x] Summary added to changelog.txt
• [x] Tests pass and coverage is not reduced
• [x] closes #37

[sourcery-ai[bot]]

Sourcery Code Quality Report

❌  Merging this PR will decrease code quality in the affected files by 0.27%.

Quality metrics	Before	After	Change
Complexity	1.31 ⭐	1.10 ⭐	-0.21 👍
Method Length	33.73 ⭐	34.78 ⭐	1.05 👎
Working memory	6.46 🙂	6.71 🙂	0.25 👎
Quality	83.24% ⭐	82.97% ⭐	-0.27% 👎

Other metrics	Before	After	Change
Lines	325	369	44

Changed files	Quality Before	Quality After	Quality Change
mf2/multi_fidelity_function.py	78.35% ⭐	80.27% ⭐	1.92% 👍
mf2/adjustable/branin.py	81.81% ⭐	80.82% ⭐	-0.99% 👎
mf2/adjustable/hartmann.py	87.40% ⭐	86.17% ⭐	-1.23% 👎
mf2/adjustable/paciorek.py	90.72% ⭐	88.78% ⭐	-1.94% 👎
mf2/adjustable/trid.py	87.50% ⭐	85.42% ⭐	-2.08% 👎

Here are some functions in these files that still need a tune-up:

File	Function	Complexity	Length	Working Memory	Quality	Recommendation
mf2/multi_fidelity_function.py	MultiFidelityFunction.__init__	5 ⭐	101 🙂	11 😞	62.01% 🙂	Extract out complex expressions
mf2/adjustable/branin.py	adjustable_branin_lf	0 ⭐	52 ⭐	11 😞	74.27% 🙂	Extract out complex expressions
mf2/multi_fidelity_function.py	AdjustableMultiFidelityFunction.__init__	1 ⭐	48 ⭐	10 😞	75.81% ⭐	Extract out complex expressions
mf2/multi_fidelity_function.py	AdjustableMultiFidelityFunction.__repr__	0 ⭐	23 ⭐	10 😞	80.90% ⭐	Extract out complex expressions

Legend and Explanation

The emojis denote the absolute quality of the code:

• ⭐ excellent
• 🙂 good
• 😞 poor
• ⛔ very poor

The 👍 and 👎 indicate whether the quality has improved or gotten worse with this pull request.

---

Please see our documentation here for details on how these metrics are calculated.

We are actively working on this report - lots more documentation and extra metrics to come!

Help us improve this quality report!