[Interactive Graph] Add logarithm graph scoring

[ivyolamit]

Summary:

PR series to add logarithm graph support to the Interactive Graph widget:

1. Add logarithm graph type definitions and data
2. Add logarithm math utilities to kmath
3. Add logarithm graph state management and reducer
4. Add logarithm graph rendering, SR strings, and equation string
5. ▶️ Add logarithm graph scoring
6. Add logarithm graph option in the Interactive Graph Editor

Add logarithm graph scoring to support the Logarithm graph in Interactive Graph

• Add logarithm scoring to score-interactive-graph.ts using direct coefficient comparison
• No canonical normalization needed (same as exponential)

Details

Follows the exponential scoring pattern exactly. Computes {a, b, c} coefficients for both the user's answer and the rubric using getLogarithmCoefficients from kmath, then compares with approximateDeepEqual.

Scoring logic:

• Returns invalid if guess coords or asymptote are missing, or if coefficient computation fails for either side
• Returns earned: 1 if [a, b, c] coefficients approximately match
• Returns earned: 0 otherwise

This means two different sets of control points that define the same logarithmic curve will score as correct — the comparison is on the mathematical function, not the specific points chosen.

Co-Authored by Claude Code (Opus)

Issue: LEMS-3953

Test plan:

• pnpm tsc passes
• pnpm knip passes
• pnpm lint passes
• pnpm prettier . --check passes
• Scoring tests pass (44 total, 6 new logarithm tests):
• Invalid: undefined guess, null coords, null asymptote
• Correct: matching coefficients
• Incorrect: different coefficients
• Equivalent curves: different control points producing same y = ln(x) coefficients → correct

[github-actions]

🗄️ Schema Change: No Changes ✅

[github-actions]

npm Snapshot: Published

Good news!! We've packaged up the latest commit from this PR (680fbf2) and published it to npm. You
can install it using the tag PR3424.

Example:

pnpm add @khanacademy/perseus@PR3424

If you are working in Khan Academy's frontend, you can run the below command.

./dev/tools/bump_perseus_version.ts -t PR3424

If you are working in Khan Academy's webapp, you can run the below command.

./dev/tools/bump_perseus_version.js -t PR3424

[github-actions]

Size Change: +42 B (+0.01%)

Total Size: 496 kB

Filename	Size	Change
packages/perseus-score/dist/es/index.js	9.7 kB	+42 B (+0.43%)

ℹ️ View Unchanged

Filename	Size
packages/kas/dist/es/index.js	20.5 kB
packages/keypad-context/dist/es/index.js	1 kB
packages/kmath/dist/es/index.js	6.35 kB
packages/math-input/dist/es/index.js	98.5 kB
packages/math-input/dist/es/strings.js	1.61 kB
packages/perseus-core/dist/es/index.item-splitting.js	12 kB
packages/perseus-core/dist/es/index.js	25.2 kB
packages/perseus-editor/dist/es/index.js	101 kB
packages/perseus-linter/dist/es/index.js	9.3 kB
packages/perseus-utils/dist/es/index.js	403 B
packages/perseus/dist/es/index.js	194 kB
packages/perseus/dist/es/strings.js	8.27 kB
packages/pure-markdown/dist/es/index.js	1.39 kB
packages/simple-markdown/dist/es/index.js	6.71 kB

_{compressed-size-action}

[github-actions]

🛠️ Item Splitting: No Changes ✅

[claude]

Claude Code Review

This repository is configured for manual code reviews. Comment @claude review to trigger a review and subscribe this PR to future pushes, or @claude review once for a one-time review.

_{Tip: disable this comment in your organization's Code Review settings.}

[ivyolamit]

@claude review once

[claude]

LGTM — straightforward addition that mirrors the exponential scoring pattern exactly, with solid test coverage.

Extended reasoning...

Overview

The PR adds logarithm graph scoring to score-interactive-graph.ts by importing getLogarithmCoefficients from kmath and inserting a new else if block following the existing exponential scoring block verbatim. A changeset file and 6 new test cases (invalid/correct/incorrect/equivalent-curve) are also included.

Security risks

None. This is pure scoring logic — no auth, no I/O, no user-controlled code paths beyond the already-gated coefficient computation.

Level of scrutiny

Low. The change is mechanical and self-contained: it adds ~30 lines of logic that are a direct copy of the adjacent exponential scoring block, only substituting getLogarithmCoefficients for getExponentialCoefficients. The pattern is already well-established and tested throughout the file.

Other factors

Test coverage is thorough for the new path (undefined guess, missing coords, missing asymptote, correct match, wrong match, and equivalent-curve normalization). Bundle size impact is negligible (+42 B). No CODEOWNERS concerns for this file.

[SonicScrewdriver]

Looks good!