“i—‑ Differential Calculus” by Abdul Matin – What It Is, Why It Matters, and How to Get It Legally 1️⃣ Who Is Abdul Matin and What Is This Book About? Abdul Matin (often listed as A. Matin in library catalogs) is a prolific author of mathematics textbooks aimed at secondary‑school and early‑university students in South Asia. His series of “i—‑” books (e.g., i—‑ Algebra , i—‑ Geometry , i—‑ Trigonometry ) has been adopted by many Bangladeshi and Indian high schools because of its clear exposition, abundant examples, and exam‑oriented practice problems.