adding atan

[gyouhoc]

Description

I add atan function in the function.py file. (issue:#972)

Fixes # (issue)

Type of change

adding arntan function

[valentinsulzer]

Thanks very much @gyouhoc ! Could you

1. Call it arctan for consistency with the other functions
2. Add a test like this one
3. Add a line to CHANGELOG.md (new feature) recording the change

[valentinsulzer]

Thanks for the update - for the test, what I meant was open the file "tests/unit/test_expression_tree/test_functions.py", then add a new function under test_arcsinh which does exactly the same thing but for arctan. Then run that test_functions python script to make sure the test you have added works. Test files should be kept separate from the source code (i.e. you don't need to add the test_functions.py file to pybamm/expression_tree, you can just add a single function to the existing test file)

[gyouhoc]

Do I run this test file from the prompt?

python test_fucntion.py gives me following error.

[valentinsulzer]

You can just run it the way you would run any python file (either from the prompt or through your IDE) - maybe you need to activate your virtual environment?

In the test you added, you should change from arcsinh to arctan (otherwise it is just a repeat of the test above it).
Also make sure that the style tests pass, you can check this locally by installing flake8 (pip install flake8) then running flake8 from command line - for example, non-empty lines raises an error, which is why this PR says "some checks were not successful"

[gyouhoc]

I did flake8 and conduct the test. I have following errors.

[valentinsulzer]

Make sure you have merged the latest version of the "develop" branch

[gyouhoc]

HI Tino,

Would you let me know how to merge the latest version of the "develop" branch?
I cloned my branch to my computer. I am a newbie to GitHub.

[valentinsulzer]

Assuming you have your fork as origin and the pybamm repository as upstream, the basic command is git fetch upstream develop: see this blog post

But I downloaded you fork and tried running the test and it works fine for me, so I don't know why you're getting that error

[gyouhoc]

can we use your test result for this change?

[valentinsulzer]

Yes, just replace all occurrences of arcsinh with arctan in test_arctan, and remove the blank spaces from lines 144 and 160 of test_functions.py (can you see the error message here?), then we can merge it

[codecov]

Codecov Report

Merging #973 into develop will increase coverage by 0.11%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #973      +/-   ##
===========================================
+ Coverage    97.36%   97.48%   +0.11%     
===========================================
  Files          222      222              
  Lines        11689    11798     +109     
===========================================
+ Hits         11381    11501     +120     
+ Misses         308      297      -11     

Impacted Files	Coverage Δ
pybamm/expression_tree/functions.py	100.00% <100.00%> (ø)
...ybamm/models/submodels/interface/kinetics/tafel.py	90.00% <0.00%> (-10.00%)	⬇️
pybamm/models/submodels/base_submodel.py	91.80% <0.00%> (-0.85%)	⬇️
...lyte_conductivity/base_electrolyte_conductivity.py	98.48% <0.00%> (-0.03%)	⬇️
pybamm/parameters/thermal_parameters.py	100.00% <0.00%> (ø)
pybamm/models/submodels/thermal/lumped.py	100.00% <0.00%> (ø)
pybamm/models/submodels/thermal/x_full.py	100.00% <0.00%> (ø)
pybamm/models/submodels/electrode/ohm/full_ohm.py	100.00% <0.00%> (ø)
...ybamm/models/full_battery_models/lead_acid/full.py	100.00% <0.00%> (ø)
... and 32 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6852e0e...9eb70c1. Read the comment docs.

[valentinsulzer]

Merging, thanks @gyouhoc !