SISO Calculator vs SolvedBooks

SISO Calculator was built to help practicing engineers and students get an intuitive sense of System Dynamics and Controls. The interface is focused so you can quickly interact with controllers and plants to see immediately how time and frequency interact and how controllers behave.

SolvedBooks is a free study companion for university and graduate students working through classic mathematics textbooks. Every solution is written from scratch by a working mathematician — not scraped, paraphrased, or copied from any publisher's solutions manual. Each exercise gets a complete worked proof in clean LaTeX, plus a brief final-answer summary. Currently covered — 1,400+ exercises: • Serge Lang — Undergraduate Algebra, 3rd Edition • Sheldon Axler — Linear Algebra Done Right, 4th Edition • John M. Lee — Introduction to Smooth Manifolds, 2nd Edition (GTM 218) • John M. Lee — Riemannian Manifolds: An Introduction to Curvature (GTM 176) How it works Question groups (5 exercises each) are locked by default. Tap "Watch ad to unlock" once per group and the unlock is permanent on your device. There is no in-app purchase to remove ads — the ads pay to maintain the app and cover more textbooks over time. What you will not find here • The original textbook problem statements — they are intentionally not reproduced • Hints, figures, or solutions copied from any publisher's manual • Accounts or cross-device sync — v1 is local-only and works offline Pen before Peek Please attempt each exercise yourself first. Productive struggle is where the mathematics lives. SolvedBooks is for the moments where you genuinely need a worked solution to keep moving forward, not a shortcut around the thinking. About the developer Built by Chris Pun, a math graduate working in differential geometry. If you find an error in a solution, or want a particular textbook covered, please get in touch — every piece of feedback is read. Independent study aid. Not affiliated with or endorsed by Springer, Pearson, Addison-Wesley, or any other publisher. All textbook titles, author names, and chapter references are used solely for identification.