Commit Checkpoint¶

You have built a complete working model: a \(q\) array, a normalized sphere form factor, a reusable plotting function, and a polydisperse extension. This is a natural checkpoint — save your work before moving on.

What to commit¶

Check what has changed since your last commit:

$ git status

You should see chapter_02_sphere.ipynb listed as a new or modified file. Stage and commit it:

$ git add chapter_02_sphere.ipynb
$ git commit -m "add sphere form factor and polydispersity model"
$ git push

Suggested commit messages for this section

If you built your notebook incrementally and want to commit at finer granularity, here are specific messages that describe each logical piece:

"add sphere form factor function" — after writing sphere_form_factor
"add log-log plotting function" — after writing plot_form_factor
"add polydisperse sphere model" — after writing polydisperse_sphere

Any of these is better than a vague message like "update notebook".

Keeping Jupyter checkpoints out of Git¶

Jupyter automatically saves checkpoint files in a hidden .ipynb_checkpoints/ folder. These are not useful to track and clutter the repository. If you did not include this in your .gitignore earlier, add it now:

.ipynb_checkpoints/

Then commit the updated .gitignore:

$ git add .gitignore
$ git commit -m "add jupyter checkpoint folder to gitignore"
$ git push

What you have built¶

After this section your notebook contains:

Function	What it does
`sphere_form_factor(q, R)`	Computes \(P(q, R)\) for a solid sphere
`plot_form_factor(q, P, ...)`	Plots a form factor on log-log axes with standard formatting
`polydisperse_sphere(q, R_mean, sigma_R)`	Averages \(P(q, R)\) over a Gaussian size distribution

These functions will be reused and extended throughout Section 4.

What's next: Section 3 → — fitting scattering models to data using least-squares optimization and extracting parameter uncertainties.