Turn handwritten maths into LaTeX on iPad
Maths is easier to think through with a pen than with a keyboard, and miserable to type up afterwards. Pen Friend lets you do the working by hand on the iPad, ask for help on the page when a step will not come, and copy the finished equation out as LaTeX in one tap.
Work it by hand
Write the problem on grid paper, the way you would on a pad. There are four papers, grid, lined, dotted and blank, and five page sizes. The canvas stays crisp however far you zoom, so small subscripts and crowded fractions stay readable.
Working from a textbook or a problem sheet? Double tap the page with a finger to paste a picture of the question. It lands as a card you can move, resize and write around.
Get unstuck without leaving the page
When you hit the step you cannot see, write the question beside it and pause. The pen friend reads the page and writes back in ink underneath, with a worked step rather than a bare answer. Ask for a diagram and it draws one with labels.
If you would rather keep the page itself clean, hold the pen button until the ring closes. A sheet of tracing paper comes down over the page, the pen friend writes and sketches on the sheet, and the page underneath stays exactly as you wrote it. Tap the button and the paper lifts away.
Copy it as LaTeX
Once the equation is right, copy it as LaTeX in one tap and paste it into a paper, a notebook or a chat. No retyping fractions, no hunting for the backslash.
The ink stays on the page, so you keep the handwritten working and the clean copy side by side, and the page can still be searched later by what it was about.
Send the whole page to your Mac
If you write next to a Mac, the free Mac companion takes the page the rest of the way. One flick sends it to the Mac clipboard, the typed text and the page images together, so the working lands in your document without a round trip through AirDrop.
What it needs
Asking the pen friend uses Google's Gemini model, and it stays off until you agree. When you ask, a picture of the page is sent so it can be read. Turn it off in Settings and nothing is sent after that; the notebook keeps working.
Pen Friend is free on the App Store for iPad, with no account and no subscription. It suits students working problem sets, people writing papers who think in equations, and anyone who keeps a worklog of calculations.
