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Proofreading pass (Task 7)

Details for Task 7 on the project board: decisions, method, progress, and the content issues raised for the author with their outcomes. The list of changes is in errata.md; the editing workflow is in CLAUDE.md.

Goal: Read every notebook in the book for typos and for content issues, and fix them in the source notebooks in ModSimPySolutions.

Scope: the source notebooks in ModSimPySolutions/, never the student copies in chapters/ and examples/ here (the build regenerates those).

  • chapters/chap01–chap27 (about 49,000 words)
  • examples/: 16 notebooks (about 13,000 words); queue is in the Jupyter Book, the rest are linked from the chapters
  • Not header.ipynb and link_header.ipynb (boilerplate), except where a fix belongs there

Decisions (2026-10-13)

  • Short links (modsimpy.com/...) live in ~/GreenTeaPress: domains/modsimpy.com/.htaccess, plus a copy for greenteapress.com/modsimpy/... in greenteapress/modsimpy/.htaccess. Keep the two in sync; deploy with scripts/deploy_gtp.sh (dry run first) after asking

  • Fixes: typos, grammar and dead links are fixed directly. Content issues (prose vs output, dated claims, exercise problems) are listed under "Content issues for the author" with a proposed fix, and changed only after approval

  • Pace: one notebook at a time: commit, then a summary of changes and open questions for review before the next

  • Order: chap01–chap27, then the examples

  • Errata: every change, typos included, goes in errata.md; the printed edition (No Starch, 2023) doesn't have them

What to check

  • Typos and grammar: spelling, repeated words, punctuation, inconsistent terms or capitalization
  • Text vs output: numbers and descriptions in the prose that no longer match what the code produces (pandas 3, NumPy 2 and SciPy changes since 2023)
  • Code that still runs but is dated: deprecated calls and warnings, things the text says about library behavior that are no longer true
  • Links: dead or redirected URLs, and data and figure URLs (ModSim repo, raw/master/... here)
  • Exercises: clear instructions; the solution matches what the exercise asks
  • Cross-references: chapter and section numbers, "in the previous chapter" and similar

Workflow (per notebook)

The .ipynb is the source; there is no jupytext pairing and no .md copies in the repo (same pattern as ElementsOfDataScience):

S=<scratchpad>
jupytext --to md -o $S/chap05.md ModSimPySolutions/chapters/chap05.ipynb
# edit $S/chap05.md
jupytext --to ipynb --update -o ModSimPySolutions/chapters/chap05.ipynb $S/chap05.md
  • --update keeps the outputs and metadata (cell tags, which hide solutions in the Jupyter Book). Never run plain jupytext --to ipynb: it discards every output
  • Markdown-only changes: no re-execution, so outputs and figures stay as they are
  • If a code cell changes, re-execute (jupyter nbconvert --to notebook --execute --inplace ...), strip the execution timestamps nbconvert adds, and check that no output recorded a local path
  • Check each round trip: only the edited cells differ (compare cell sources before and after), and the number of outputs is unchanged
  • Run pytest --nbmake on the notebook before committing

jupytext is in environment-dev.yml (added 2026-10-13; 1.19.6 installed locally).

Commits and pushes

  • One commit per notebook in ModSimPySolutions, listing what changed and any content issues left for the author
  • Push rarely (each push runs CI); rebuild the student notebooks and the site with make build at the end, or at milestones

Progress

Pushed after chap10 (2026-10-13): both repos, one push each; student notebooks and the site not rebuilt yet.

Released after chap27 (2026-10-13): ModSimPySolutions and ModSimPy pushed (CI passed on both); student chapters and examples, the notebook zip and modsim.py regenerated; site rebuilt and published (chapter numbers, all fixes; Pages deploy checked live); short links /minmod, /cdc, /minimize deployed (GreenTeaPress 2f9dd77). All 44 solution notebooks passed nbmake locally first.

Released after the examples (2026-10-13): make build end to end (with the build-script fix, it skipped the empty commits instead of stopping): ModSimPySolutions and ModSimPy pushed once each, CI passed on both; student examples regenerated (no solutions, no outputs); site rebuilt and checked live (e.g. queue). All 44 solution notebooks passed nbmake locally first.

Build snag: make build stops when a build script has nothing new to commit (the scripts run git commit unconditionally and exit with its status), e.g. when the exported chapNN.py are unchanged. This time the steps were run by hand in the Makefile's order. Fix: make those commits conditional (git diff --cached --quiet || git commit ...). Fixed 2026-10-13 in chapters/build.sh, examples/build.sh and ModSimPySolutions/chapters/build.sh.

Notebooks Status
chap01 done (ModSimPySolutions 32a51be, content fixes in the next commit)
chap02 done (ModSimPySolutions 8303751); content fix in the next commit
chap03 done (ModSimPySolutions 4a487e4); no content issues
chap04 done (ModSimPySolutions 09930a8 and the next commit)
chap05 done (ModSimPySolutions 775a602); no content issues
chap06 done (ModSimPySolutions 42c70f0, 792001b)
chap07 done (ModSimPySolutions 1385073 and the next commit)
chap08 done (ModSimPySolutions 3ea71b0 and the next commit)
chap09 done (ModSimPySolutions 7cf4af4 and the next commit)
chap10 done (ModSimPySolutions 199fc93 and the next commit; re-executed)
chap11 done (ModSimPySolutions 149cee0, 6490eb4)
chap12 done (ModSimPySolutions d06ddb3, 690f145)
chap13 done (ModSimPySolutions dee3e7f); no content issues
chap14 done (ModSimPySolutions 6bfcf9f, 4a65094, and the next commit)
chap15 done (ModSimPySolutions c4c9907, 335dcdb; re-executed)
chap16 done (ModSimPySolutions 94a41db, 8321b6d; re-executed)
chap17 done (ModSimPySolutions 97c752b, adeda99); short links deployed
chap18 done (ModSimPySolutions 866e2ce, 22bdca1; re-executed)
chap19 done (ModSimPySolutions 4ce0858); no content issues
chap20 done (ModSimPySolutions fa03e2c, 8a36d9e; re-executed)
chap21 done (ModSimPySolutions 170aa03, 9220418; re-executed)
chap22 done (ModSimPySolutions 2200872, 5fe402d; re-executed)
chap23 done (ModSimPySolutions 6fa5b26, a4d94c3); short link deployed
chap24 done (ModSimPySolutions 11c6cc2, 4c8c42c)
chap25 done (ModSimPySolutions 2d5c3d6, 1e3b20d)
chap26 done (ModSimPySolutions 6520729); no content questions
chap27 done (ModSimPySolutions 24d8087)
examples/bungee1 done (ModSimPySolutions cd4a948, 4fdb76f)
examples/bungee2 done (ModSimPySolutions b1217d5, 2463673; re-executed)
examples/filter done (ModSimPySolutions bbb9eb9, 4c71f98)
examples/glucose done (ModSimPySolutions 1bcc911, 64698f9; re-executed)
examples/hiv_model done (ModSimPySolutions a47420c); no content questions
examples/insulin done (ModSimPySolutions f8e8983)
examples/kitten done (ModSimPySolutions eac904a); no content questions
examples/orbit done (ModSimPySolutions 3f8cf4e); no content questions
examples/plague done (ModSimPySolutions 5fb8d84); no content questions
examples/queue done (ModSimPySolutions aea2509, 2182ff9; re-executed)
examples/salmon done (ModSimPySolutions 4e6abd1; re-executed); no content questions
examples/spiderman done (ModSimPySolutions a5c25ba, 64364b5; re-executed)
examples/throwingaxe done (ModSimPySolutions cd5a64a, 959405d; re-executed)
examples/trees done (ModSimPySolutions 086c633); no content questions
examples/wall done (ModSimPySolutions b205eeb, 082cf55)
examples/yoyo done (ModSimPySolutions 479920f); no content questions
all chapters and examples done (2026-10-13); header.ipynb skipped (boilerplate)

Content issues for the author

Items that need a decision rather than an obvious fix. Mark each open, approved or declined.

chap01

  1. approved: describe Veritasium · The Falling Penny Myth: the text says Mythbusters tested the myth and gives https://modsimpy.com/myth/ for "the results", but that short link redirects to a Veritasium video ("How Dangerous is a Penny Dropped From a Skyscraper?"). Either point the link at the Mythbusters segment or change the text to describe the Veritasium video. The short link is on modsimpy.com, so it can be fixed without changing the notebook. (The 29 m/s terminal velocity matches the 64.4 mph Mythbusters estimate.)
  2. approved: CC BY-NC-SA 4.0 (README fixed; it now also says the code is MIT, as LICENSE says) · License: the notebook header says CC BY-NC-SA 4.0; the README says CC BY-NC 4.0. Probably shared by every notebook's header, so decide once for the whole book.
  3. approved: rewritten for Colab and JupyterLab · More Jupyter (hidden in the book, shown to students): the instructions are for the classic Notebook interface ("Insert cell below" in the Insert menu, "Close and Halt", "Restart & Run All"), which Notebook 7, JupyterLab and Colab don't have. Proposed: rewrite briefly so it works for Colab and JupyterLab.
  4. declined · Exercise 8 solution uses round to split the pace into minutes and seconds. That works for 7.22 min/mile but would give a negative remainder for, say, 7.6. Proposed: floor instead of round (and import floor from NumPy rather than shadowing the built-in round).

chap02

  1. approved: delete the second · Modeling a Bike Share System: the same point is made twice in a row. "...in a State object, which gets assigned to a new variable named bikeshare." and, two sentences later, "The State object is assigned to a new variable named bikeshare." Proposed: delete the second sentence.

chap04

  1. approved: reword · Exercise 6 asked for "a range of values for p1 and p2" but only sweeps p1.
  2. approved: short answer · Exercise 6's solution didn't answer "What value of p1 minimizes...?"

chap06

  1. approved: fix both · The text and the Exercise 1 solution docstring said the growth function computes next year's population; it returns the net growth.

chap07

  1. approved: drop the sentence · The introduction promised an exercise on a time-varying growth rate that isn't in this chapter.
  2. approved: change the text · Exercise 2 said 1 to 20 billion; the solution uses 1 to 25.

chap08

  1. approved: move it · The notebook notice was in the Exercises section instead of after the introduction.

chap09

  1. approved: "previous chapters" · "The population models in the previous chapter and this one" (this chapter has no new model).
  2. Notebook notice moved, applying the chap08 decision.

chap10

  1. approved: fix and re-execute · Wrong title on the 1940-present solution plot.

chap11

  1. approved · Peak timing: 35 days → 30 days.
  2. approved: fix all three · run_simulation1 named as run_simulation, and "values of 0 and t_end".
  3. approved: add the count · Exercise 1 asks how many students; the solution gave a fraction.
  4. done · http://modsimpy.com/sir redirected to maa.org, which returns 403 Forbidden (at least to scripts). Now points to https://sites.math.duke.edu/education/postcalc/sir/index.html (same article). Deployed 2026-10-13, GreenTeaPress 241076f.

chap12

  1. approved: increase in gamma, with the mechanism explained · The quarantine solution said "reduction in gamma" but the code raises gamma. Discussed lowering beta instead: that models fewer contacts for every infected student (distancing), not isolating identified cases; for the total-infected metric both give the same result when beta/gamma is the same.

chap14

  1. approved after discussion · The $c &lt; 1$ discrepancy is due to the size of the initial infection, not discrete time; reworded as above.
  2. approved after discussion · The steep-curve example: 25%–60% infected → $c$ near 1.3. The bullet shows that in the steep part, a wide (noisy) range of observations still gives about the same $c$; the flat part (second bullet) is where $c$ is hard to estimate.

chap15

  1. approved · Temperature relates to average kinetic energy, not average velocity.
  2. approved: fix and re-execute · Exercise 2 solution didn't assign the root_scalar result.
  3. approved: drop the Exercises copy · Chapters 15–27 have the notebook notice twice; keep only the one after the introduction (applies to every remaining chapter).
  4. approved · NumPy 2 scalar display: np.set_printoptions(legacy="1.25") in modsim.py.

chap16

  1. approved · Mix last now simulates the milk for 30 minutes: 62.9 → 63.2 °C.
  2. declined · "identical ... with a small difference due to rounding" kept as is.

chap17

  1. approved · $X(0) = I_b$ → $X(0) = 0$.
  2. approved: drop "PDF at" · Dead PDF link; /minmod redirected to the abstract.
  3. approved: PubMed · The MINMOD citation linked a different paper.
  4. approved: update both · Diabetes prevalence 10% → 12%; /cdc redirected to the current report.

chap18

  1. approved · X declines with blood insulin, not glucose.
  2. approved: drop it · The hidden G-minus-X comparison cell (a relative comparison of X is meaningless because X starts at 0).

chap20

  1. approved · Exercise 1 solution computed the answer in days but didn't display it.

chap21

  1. approved: fix and re-execute · params overwritten in Exercise 1, leaking v_init=-30 into Exercise 2.
  2. approved · error_func docstring.
  3. approved: "near the low end" · 40 mph is not the low end of 35–65 mph.

chap22

  1. approved: fix all and re-execute · Three slips in the solution code (details for details2; old functions tested in Exercise 3).

chap23

  1. approved · The arguments of maximize_scalar were described wrongly.
  2. approved: Brent's method · /minimize → https://en.wikipedia.org/wiki/Brent_method (redirects to "Brent's method"; ASCII-only, to keep %27 out of the .htaccess).

chap24

  1. approved: "earlier in the chapter" · "Section xxx" placeholder.
  2. approved: renumber · "Dividing Equations 1 and 2" referred to the wrong Equation 1.

chap25

  1. approved · 0.333 is a little more than the guess of 0.3.
  2. approved: say "mass" · Masses in kg were called weights.

chap27

  1. declined · "evaluates the slope function seven times" per step (six new evaluations, since the last is reused); kept as a fair simplification.

examples/bungee1

  1. approved: match the code · Parameter list had L = 40 m, k = 20 N/m.
  2. approved: replace · Obsolete note about zero_force and units.

examples/bungee2

  1. approved: test at 54 · Spring-force test didn't match the text.
  2. approved · Stale note about an event function in Phase 2.

examples/filter

  1. approved: simpler · Unfinished tau bullet.
  2. approved · Stale t_eval=ts suggestion.
  3. approved · Offset approaches -90 degrees.

examples/glucose

  1. approved · Fit plot showed the starting parameters.
  2. declined · Minus sign in $S \equiv -\delta E / \delta I$ kept as is.

examples/insulin

  1. declined · The normal-range citation ("Pacini and Bergman") links a ResearchGate paper with a different title; kept as is.

examples/queue

  1. approved: fix and re-execute · Test runs reused stale results.

examples/spiderman

  1. approved: code to 76 · Mass 75 kg in the code vs 76 kg in the text.
  2. approved · The 1-D spring force is in the bungee case studies, not Chapter 21.
  3. approved: drop it · Orphan sentence.

examples/throwingaxe

  1. approved · The "final state" figure drew the initial state.
  2. approved: reword · No make_system in this notebook.
  3. declined · Target "typically 6 m away" vs 8 m in the simulation; left as is (open-ended exercise).

examples/wall

  1. approved: remove · Obsolete paragraph about units.

Book-wide: display math format (ModSimPySolutions 6ffa856)

  • VS Code showed a KaTeX ParseError in chapter 18 (The Update Function). Rather than depend on each reader's setup, every $$...$$ block now has the delimiters on their own lines, with no trailing spaces. Markup only (57 cells in 19 notebooks). The two \label{} in chap24 (unreferenced; unsupported by KaTeX) are removed
  • Checked by rendering every markdown cell with VS Code's notebook renderer settings (@vscode/markdown-it-katex, KaTeX 0.16.21, throwOnError, bare and fenced blocks): 0 errors (was 2, in chap24). Jupyter Book (MathJax) builds with all math rendered. Confirmed working in VS Code
  • Jupyter Book chapter numbers (ModSimPy 6d58752): numbered: True on the Chapters part of jb/_toc.yml, preface in its own Front Matter part (as in ThinkBayes2). Test build shows "18. Glucose and Insulin", sections 18.1, ...; live on the next site build

Notebook-only changes

Changes that don't affect the printed book, so they are not in errata.md: solutions, hidden cells, notebook layout, modsim.py, and the examples.

chap01

  • More Jupyter (content; not in the printed book): classic-Notebook menu steps replaced with Colab and JupyterLab steps

chap04

  • Exercise 6 solution (content; solutions aren't in the printed book): added the answer, "The minimum is near p1 = 0.35, close to p2 = 0.3."

chap06

  • Exercise 1 solution docstring (content; not in the printed book): "Compute the population next year ... returns: population next year" → "Compute the net growth during the current year ... returns: net growth"

chap08

  • Layout (content): the "This chapter is available as a Jupyter notebook" note moved from the start of Exercises to after the introduction, with the same wording as the other chapters

chap09

  • Layout (content): notebook notice moved from Exercises to after the introduction (same as chap08)

chap10

  • Solution plot (content; not in the printed book): the 1940-present plot was titled "Prehistoric population estimates" → "Model vs. estimates since 1940". Notebook re-executed; the other three figures were re-rendered by current Matplotlib with no visible change

chap11

  • Exercise 1 solution (content; not in the printed book): added "About 38% of the class, or 34 of the 90 students, get infected."
  • Layout (content): notebook notice moved from Exercises to after the introduction (same as chap08)

chap12

  • Exercise 1 solution (content; not in the printed book): "model quarantine as an effective reduction in gamma" → "an effective increase in gamma", with an explanation: R means "removed", quarantined students can't infect anyone, so a shorter time in the infectious compartment is a shorter recovery time and a higher gamma = 1/tr
  • Layout (content): notebook notice moved from Exercises to after the introduction (same as chap08)

chap13

  • Layout (content): notebook notice moved from Exercises to after the introduction (same as chap08)

chap14

  • Layout (content): notebook notice moved from Exercises to after the introduction (same as chap08)

chap15

  • Exercise 2 solution (content; not in the printed book): root_scalar(...) → res = root_scalar(...); the displayed res had been the coffee result. Re-executed: res.root is 0.133 for the milk
  • Layout: the second notebook notice (in Exercises) removed; chapters 15–27 have one after the introduction (tagged remove-print) and one in Exercises

chap16

  • Layout: duplicate notebook notice removed from Exercises

chap17

  • Layout: duplicate notebook notice removed from Exercises

Book-wide: NumPy 2 scalar display (ModSimPy c91e8e1)

  • NumPy 2 shows scalars as np.float64(72.3) where the book shows 72.3, for every reader with current NumPy (Colab included). modsim.py now calls np.set_printoptions(legacy="1.25"). Readers get it once ModSimPy is pushed (the notebooks download modsim.py from master)
  • Re-executed notebooks now match the book; SciPy's root_scalar result also prints slightly differently now (flag: converged, plus method: brentq)

chap18

  • Hidden cell (content; not in the printed book): removed a comparison that computed results.G - results2.X (mean inf); re-executed
  • Layout: duplicate notebook notice removed from Exercises

chap20

  • Exercise 1 solution (content; not in the printed book): now displays the answer in days, 64.8; re-executed
  • Layout: duplicate notebook notice removed from Exercises

chap21

  • Exercise 1 solution (content; not in the printed book): params = params.set(v_init=-30) overwrote params, so in Exercise 2 the quarter was thrown down at 30 m/s. Now params2 = .... Exercise 2's answer changes from v_term = 19.5 m/s, C_d = 0.54 to v_term = 21.7 m/s, C_d = 0.44 (the same as the penny). Re-executed
  • Exercise 2 solution (content; not in the printed book): error_func docstring said "Final height as a function of C_d ... returns: height in m" → "Error in flight time as a function of v_term ... returns: difference between simulated and measured flight time in s"
  • Layout: duplicate notebook notice removed from Exercises

chap22

  • Solutions (content; not in the printed book): Exercise 1 displayed details.message → details2.message; Exercise 3's test cells called drag_force and slope_func → drag_force2 and slope_func2. Re-executed; the stored outputs had been made under NumPy 2 before the modsim.py fix and showed np.float64(...)
  • Layout: duplicate notebook notice removed from Exercises

chap23

  • Layout: duplicate notebook notice removed from Exercises

chap24

  • Display math: the two unused \label{} removed (book-wide math change)
  • Layout: duplicate notebook notice removed from Exercises

chap25

  • Layout: duplicate notebook notice removed from Exercises

examples/bungee1 (not in the printed book)

  • "in the opposite of their direction of motion" → "opposite to their direction of motion"; "a Param object" → "a Params object"; "springs back almost to almost 70 m" → "almost to 70 m"; "more oscillation that we expect" → "than we expect"; "the numerical derivative of ys" → "of results.v"; docstring "from system|" → "from system:"
  • event_func.direction = 10 → 1, matching the text ("The value 1 (or any positive value)")
  • (content) The parameter list said L = 40 m and k = 20 N / m; the code uses 25 m and 40 N/m → list matches the code; "With a terminal velocity of 60 m/s." → "Let's assume the jumper's terminal velocity is 60 m/s."
  • (content) Removed "returns zero_force, which is either 0 Newtons or 0, depending on whether the System object has units..." → "If the cord is not extended, it returns 0."

examples/bungee2 (not in the printed book)

  • Same slips as bungee1: "in the opposite of their direction" → "opposite to"; "Param" → "Params"; missing period; also "The jumpers's" → "The jumper's"
  • cord_acc docstring: "Computes the force of the bungee cord ... velocity of the jumpter ... acceleration in m/s" → "Computes the acceleration of the jumper due to the cord ... velocity of the jumper ... acceleration in m/s**2"
  • (content) The spring-force test used spring_force(56) (1 m above full extension, giving -40) under text that says 1 m of extension gives 40 N → spring_force(54). Re-executed
  • (content) "Here's how we run Phase 2, setting the direction of the event function so it doesn't stop the simulation immediately." → "Here's how we run Phase 2." (Phase 2 has no event function)

examples/filter (not in the printed book)

  • "a circuit takes a signal" → "a circuit that takes a signal"; "audio signal" → "audio signals"; "pass the Params object make_system which" → "to make_system, which"; missing period; "is call" → "is called"; "functions that ... returns" → "return"; estimate_offset docstring "returns: amplitude ratio" → "phase offset in degrees"
  • (content) The tau bullet stopped mid-sentence → "which determines how long the initial startup phase lasts."
  • (content) Dropped "I suggest using t_eval=ts..." (no ts; the notebook uses num=401)
  • (content) "For high frequencies, it approaches 90 degrees" → "-90 degrees"
  • The two electronics-tutorials.ws links couldn't be checked (the site hangs for scripts)

examples/glucose (not in the printed book)

  • "In the previous chapter" → "In Chapter 18"; "Levenberg-Marquart" → "Levenberg–Marquardt"; "at the some time stamps" → "at the same timestamps"; pandas iloc link → https://pandas.pydata.org/docs/user_guide/indexing.html#selection-by-position (the old anchor is gone)
  • (content) The plot after fitting showed results.G (the starting parameters) → results2.G (the best fit). Re-executed; leastsq under current SciPy gives the same fit to about five significant digits (SSE 318.15 vs 318.13)

examples/hiv_model (not in the printed book)

examples/insulin (not in the printed book)

  • "In Chapter 17 I present" → "I presented"; "time stamp" → "timestamp" (twice; "evaluated as the same" → "at the same"); error_func docstring "actual: array of values" → "data: DataFrame of values"; "For $I_{max}$ is the maximum" → "$I_{max}$ is the maximum"

examples/kitten (not in the printed book)

  • "Mcore is the weight of the core ... Mroll is the total weight" → "mass" (as in chap25)
  • (content) "$r_2$ is the outer diameter, and $r_1$ is the inner diameter" → "radius" (the formula uses $r^4$ with radii); "Since the outer diameter changes" → "outer radius"

examples/orbit (not in the printed book)

  • universal_gravitation docstring "State object with distance r" → "with x, y, vx, and vy"; "the earth" → "the Earth"; 'DOP853' → DOP853

examples/plague (not in the printed book)

  • logistic docstring "generalize" → "generalized"; "fraction and the remaining" → "fraction, and the remaining"; "$50" → "$50" (escaped, like the other amounts)

examples/queue (in the Jupyter Book, not in the printed book)

  • "the bikeshare model ... any timestep" → "the bike share model ... any time step"; alt text for the scenarios figure (was empty); "f you are not sure" → "If you are not sure"; update_func3 comments "the first servers is busy, check it it's done" → "the first server is busy, check if it's done", "the second queue is busy" → "the second server"; a missing "?"
  • (content) The two-server and two-queue test cells called run_simulation(...) without assigning results, so they plotted and measured the single-server run → results = run_simulation(...). Re-executed (no random seed, so all random outputs changed; the conclusion holds: two queues 6.53 min vs one queue 6.34 min, "slightly higher")

examples/salmon (not in the printed book)

  • Plot title 'Narraguacus River' → 'Narraguagus River'; "from year-to-year" → "from year to year"; "functon" → "function"; missing period; "to run generate" → "to generate"; "substract" → "subtract"; "The plot option alpha=0.1" → "alpha=0.3" (as in the code); run_simulation docstring "Simulate a queueing system" → "Simulate the population over time"
  • The USASAC report link (dead; redirected to a generic NOAA page) → NOAA's Atlantic Salmon Assessments page, https://www.fisheries.noaa.gov/resource/document/atlantic-salmon-assessments (the 2017 report itself is probably in the NOAA repository, which blocks scripts; a copy is in ~/ModSimPy-attic/data/); NumPy random.choice docs link (404) → current location
  • Re-executed for the title fix (no random seed; the claims hold: median net change negative, decline vs growth 0.64 vs 0.36, "about 2:1")

examples/spiderman (not in the printed book)

  • Spider-Man wiki link wikia.com → fandom.com; missing periods; spring_force docstring "Compute drag force" → "Compute spring force"; "a function that takes t_release and V_0" → "and params"
  • (content) "Spider-Man weighs 76 kg" but mass = 75 in the code → "has a mass of 76 kg" and mass = 76 (as in chapter 26). Re-executed; the best range changes from 149.5 m to 149.4 m
  • (content) "We saw the 1-D version in Chapter 21" → "in the bungee jumping case studies"
  • (content) Removed an orphan sentence, "We can extract the x and y components as Series objects."

examples/throwingaxe (not in the printed book)

  • State variables listed in code order (x, y, vx, vy, theta, omega); a doubled slash in a figure URL
  • (content) "Here's a version of make_system that sets the initial conditions" (there is none) → "Here are the parameters and initial conditions."
  • (content) "Here's the final state of the axe at the point of impact" drew system.init → draws results.iloc[-1] at t_end. Re-executed

examples/trees (not in the printed book)

  • Dead links: the Flewelling et al. working paper (UW, 404) → Wayback copy from 2015 (the 2022 snapshot is a captured 404); Garcia (1983), citeseerx (404) → https://doi.org/10.2307/2531339; EasySDE site (forestgrowth.unbc.ca, no longer resolves) → Wayback copy from 2021
  • run_simulation docstring "computes the population next year" → "the height next year"; "logisitic" → "logistic"; a missing colon; "Open Exercise" → "Open Exercise:"
  • Checked: fitted dimension 3.11 (Model 2) and 2.64 (Model 3, "about 2.6") match the text; the analysis derivations check out

examples/wall (not in the printed book)

  • "[which I downloaded here]" → "[available here]"; "timesteps" → "time steps"; "packs the parameters into Series objects" → "into tuples"; docstrings copied from other examples ("state: position, velocity", "returns: derivatives of y and v", "params: Params object") → describe this code; missing periods
  • (content) Removed an obsolete paragraph about units and require_units (nothing in the notebook uses units)

examples/yoyo (not in the printed book)

  • "rolled up string" → "rolled-up string"; "counter-clockwise" → "counterclockwise" (twice), as in chapter 26
  • Checked: inline math written with spaces inside the delimiters ($ a = -r \alpha $) renders in VS Code's KaTeX, so it was left as is