This online Textbook based on half-year senior undergraduate / 1-st year graduate course APM441/MAT1507 at Department of Mathematics, University of Toronto but contains some additions. I taught this class in Spring of 2016 and Fall of 2024.
I am also creating a pdf verssion and upload it to AMS Open Math Notes.
This Textbook is open (which means that anyone can use it without any permission or fees) and open-source (which means that anyone can easily modify it for his or her own needs) and it will remain this way forever. Source (in the form of Markdown) of each page could be downloaded: this page's URL is
http://www.math.toronto.edu/ivrii/APM-textbook/Chapter0/L01.html
and its source's URL is
http://www.math.toronto.edu/ivrii/APM-textbook/Chapter0/L01.md
and for all other pages respectively.
Victor Ivrii
Department of Mathematics
University of Toronto
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.