Elementary Calculus: An Infinitesimal Approach
Elementary Calculus: An Infinitesimal Approach by Keislerby Keisler
Ranked 4 of 4 calculus textbooks by recommenders
People recommend it as a fairly well-regarded calculus textbook that is available online.
3 people recommended Elementary Calculus: An Infinitesimal Approach by Keisler in Hacker News comments and none criticized it, November 2025 to October 2026.
2 of the 3 people who recommend it commented in one thread, “Simplifying and Refactoring Introductory Calculus”.
Summary written by Claude from 1 comment.
3 people gave an opinion
- recommend it
- 3
- mixed feelings
- 0
- warn against or regret it
- 0
The record
Recommended in 2 of 12 months
In 2 different threads.
- November 2025: not recommended
- December 2025: not recommended
- January 2026: not recommended
- February 2026: not recommended
- March 2026: not recommended
- April 2026: not recommended
- May 2026: not recommended
- June 2026: not recommended
- July 2026: not recommended
- August 2026: recommended
- September 2026: recommended
- October 2026: not recommended
Why it doesn’t carry the badge
- 3 people recommend itNeeds 10 or more, not met.
- Nobody criticizes itNeeds 2 to 1 or better, met.
- Recommended in 2 of 12 monthsNeeds 4 or more, not met.
- Recommended in 2 threadsNeeds 5 or more, not met.
- 2 of its 3 recommenders came from one threadNeeds half or less, not met.
The same rules apply to every product, and the badge can’t be bought. Mixed feelings count toward neither side. How the badge works
What people say about it
Reasons grouped from a sample of 1 of the 3 opinions about it, picked in proportion to how many people recommend it, have mixed feelings and criticize it. Each mark is one comment in the sample. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Well-regarded calculus textbook
“there's a fairly well-regarded textbook available online”
Comment from 15 Sep 2026 in “Jean-Pierre Serre turns 100”
Other calculus textbooks people recommend
The three most recommended other calculus textbooks, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
| Product | Recommend | Mixed | Criticize | Approval | Months | Had for | Badge |
|---|---|---|---|---|---|---|---|
| Calculusby James Stewart | 9 | 1 | 3 | 75% | 4 | — | — |
| Calculus Made Easyby Silvanus P. Thompson | 5 | 0 | 1 | 83% | 3 | — | — |
| Calculus for Mathematicians, Computer Scientists, and Physicistsby Daniel Flegg | 4 | 0 | 4 | 50% | 1 | — | — |
| Elementary Calculus: An Infinitesimal Approachby KeislerThis page | 3 | 0 | 0 | 100% | 2 | — | — |
What people said
1 of the 3 opinions about it, picked in proportion to the three counts, newest first. Each links to the original comment.
“there's a fairly well-regarded textbook available online”
Counts come from 1,791,911 Hacker News comments labeled by Claude, November 2025 to October 2026, with data through October 31, 2026. Counts updated 2 Nov 2026. How we count. Report a mistake.