Linear Methods of Applied Mathematics
Textbook suitable for a first course on partial differential equations, Fourier series and special functions, and integral equations by Evans M. Harrell II and James V. Herod. HTML, RTF and PDF with Maple and Mathematica worksheets.
http://www.mathphysics.com/pde/
Generatingfunctionology
By Herbert S. Wilf. Published by Academic Press. PDF.
http://www.math.upenn.edu/~wilf/DownldGF.html
Euclid's Elements
Edited by D.E. Joyce. HTML text with Java applets.
http://aleph0.clarku.edu/~djoyce/java/elements/toc.html
Fundamentals of Model Theory
Introductory textbook by William Weiss and Cherie D'Mello. PostScript, DVI, GIF.
http://at.yorku.ca/i/a/a/i/10.htm
Probability
"Introduction to Probability" by Charles M. Grinstead and J. Laurie Snell in PDF. Published by the AMS. The site also contains additional teaching resources.
http://www.dartmouth.edu/~chance/teaching_aids/books_articles/probability_book/book.html
A=B
Combinatorics text by Marko Petkovsek, Herbert Wilf and Doron Zeilberger. Published by A. K. Peters. PDF.
http://www.cis.upenn.edu/~wilf/AeqB.html
Numerical Recipes Books On-Line
The complete Numerical Recipes books in C, Fortran 77, and Fortran 90 On-Line, in both PostScript and Adobe Acrobat formats.
http://www.nr.com/nronline_switcher.html
Mixed Motives
Monograph by Marc Levine published by AMS in 1998. Whole book or chapters in PDF.
http://www.ams.org/online_bks/surv57/surv57.pdf
Tensor Calculus and Continuum Mechanics
Textbook by John H. Heinbockel. Whole book or chapters in PostScript and PDF.
http://www.math.odu.edu/~jhh/counter2.html
Practical Foundations of Mathematics
An account of the foundations of mathematics (algebra) and theoretical computer science, from a modern constructive viewpoint by Paul Taylor. Published by Cambridge University Press. HTML approximation.
http://www.dcs.qmw.ac.uk/~pt/Practical_Foundations/html/summary.html
Elements of Abstract and Linear Algebra
Foundational textbook on abstract algebra with emphasis on linear algebra by Edwin H. Connell. Whole book or chapters in DVI, PostScript, and PDF.
http://www.math.miami.edu/~ec/book/
Universal Algebra
"A Course in Universal Algebra" by Stanley Burris and H. P. Sankappanavar. PostScript and PDF.
http://www.thoralf.uwaterloo.ca/htdocs/ualg.html
C*-Algebras
"An Introduction to C*-Algebras" by Pierre de la Harpe and Vaughan Jones. The site is in French, but the book is in English. Chapters in PostScript.
http://www.unige.ch/math/biblio/preprint/cstar/liste.html
Templates for the Solution of Linear Systems
Book on iterative methods by Richard Barrett et al. in HTML and Postscript.
http://netlib2.cs.utk.edu/linalg/html_templates/Templates.html
Semi-Simple Lie Algebras and their Representations
Book for particle physicists by Robert N. Cahn. Published by Benjamin-Cummings in 1984. Chapters in PostScript.
http://www-physics.lbl.gov/~rncahn/book.html
Abstract Algebra II
A companion volume to "Abstract Algebra" by John A. Beachy and Bill Blair published by Waveland Press in 1995. Chapters in PostScript.
http://www.math.niu.edu/~beachy/abstract_algebraII/
Linearization via the Lie Derivative
By Carmen Chicone and Richard Swanson. LaTeX, DVI, PostScript and PDF.
http://ejde.math.swt.edu/Monographs/02/abstr.html
Multivariable Calculus
Textbook by George Cain and James Herod. Chapters in PDF.
http://www.math.gatech.edu/~cain/notes/calculus.html
Topology Course Lecture Notes
By Aisling McCluskey and Brian McMaster. HTML with symbol fonts, DVI and PostScript.
http://at.yorku.ca/i/a/a/b/23.htm
Trigonometry
"Dave's Short Trig Course" by D. E. Joyce. HTML with Java.
http://aleph0.clarku.edu/~djoyce/java/trig/
Analysis WebNotes
Online course by John Lindsay Orr. Chapters also available in LaTeX.
http://www.math.unl.edu/~webnotes/home/home.htm
Advanced Calculus and Analysis
Lecture notes by Ian Craw from a course at the Univ. of Aberdeen. HTML with GIFs.
http://www.maths.abdn.ac.uk/~igc/tch/ma2001/notes/notes.html
Interactive Real Analysis
"Interactive Real Analysis" by Bert G. Wachsmuth. HTML and Java.
http://www.shu.edu/html/teaching/math/reals/reals.html
Complex and Functional Analysis
Lecture notes by Douglas N. Arnold for a course at Penn State. Two parts in TeX, DVI, PostScript and PDF.
http://www.math.psu.edu/dna/502.s97/
Category Theory
"A Gentle Introduction to Category Theory - the calculational approach" by Maarten M. Fokkinga in PostScript.
http://wwwhome.cs.utwente.nl/~fokkinga/mmf92b.html
Multiplier Ideals for Algebraic Geometers
Draft of a part of a book in preparation on positivity in algebraic geometry by Robert Lazarsfeld. DVI and PostScript.
http://www.math.lsa.umich.edu/~rlaz/
Dynamical Systems
1927 classic by George D. Birkhoff published by AMS. Scanned chapters in PDF.
http://www.ams.org/online_bks/coll9/
Functional Analysis and Semi-Groups
Book by Einar Hille and Ralph S. Phillips published by AMS in 1957. Scanned chapters in PDF.
http://www.ams.org/online_bks/coll31/
Global Analysis
"The Convenient Setting of Global Analysis" - foundations of differential calculus in infinite dimensions with applications to differential geometry and global analysis by Andreas Kriegl and Peter W. Michor published by AMS in 1997. Whole book
http://www.ams.org/online_bks/surv53/
Complex Dynamics in Higher Dimensions
CBMS lecture notes by John Erik Fornæss at the bottom of page with other papers by the author and Nessim Sibony. PostScript.
http://www.math.lsa.umich.edu/~fornaess/complexdynamicspapers.html
Several complex variables
Several sets of lecture notes by Jean-Pierre Demailly, some in French, including "Potential theory in several complex variables", and "Multiplier ideal sheaves and analytic methods in algebraic geometry" in DVI or PostScript.
http://www-fourier.ujf-grenoble.fr/~demailly/lectures.html
Algebraic Topology
1942 classic by Solomon Lefschetz published by AMS. Chapters in scanned PDF.
http://www.ams.org/online_bks/coll27/
Travelling Wave Solutions of Parabolic Systems
Translation of a monograph by Aizik Volpert, Vitaly Volpert, and Vladimir Volpert published by AMS in 1994. Whole book or chapters in PDF.
http://www.ams.org/online_bks/mmono140/
Differential Topology
Course notes by Matthew G. Brin in PostScript including "Introduction to Differential Topology", "Introduction to Seifert fibered 3-manifolds", "Groups acting on 1-dimensional spaces", and "Presentations, conjugacy, roo
http://www.math.binghamton.edu/matt/
History of Calculus
Guide To History of Calculus. Topic essays and biographies keyed to the chapters and content of the 10th edition of Thomas's Calculus.
http://occ.awlonline.com/bookbind/pubbooks/thomas_awl/chapter1/medialib/custom3/deluxe-content.html
Mathematical Methods of Engineering Analysis
Book by Erhan Çinlar and Robert J. Vanderbei in PDF. Topics covered: functions on metric spaces, differential and integral equations, convex analysis, and measure and integration.
http://www.sor.princeton.edu/~rvdb/506book/book.pdf
Numerical Analysis
"Introduction to Numerical Analysis Using Maple" by Barry G. Adams in HTML.
http://www.cs.laurentian.ca/badams/numeric/intro/intro.html
Dynamical Systems and Fractals
Lecture Notes by David J. Wright in HTML.
http://www.math.okstate.edu/mathdept/dynamics/lecnotes/lecnotes.html
Geometric Constraint Solving
An electronic primer by William Bouma, Xiangping Chen, Ioannis Fudos, Christoph Hoffmann, and Pamela J. Vermeer.
http://www.cs.purdue.edu:80/homes/cmh/electrobook/intro.html
The Limits of Mathematics
An online course on information theory and the limits of formal reasoning by G.J. Chaitin.
http://www.umcs.maine.edu/~chaitin/lm.html
Hilbert Space Methods for Partial Differential Equations
Textbook for beginning graduate students of mathematics, engineering, and the physical sciences by Ralph Showalter. Chapters in PostScript and PDF.
http://ejde.math.swt.edu/Monographs/01/abstr.html
Plane Geometry
Shalosh B. Ekhad XIV. A fully illustrated and completely self-contained Elementary Geometry textbook (ca. 2050), downloaded from the future by Doron Zeilberger. Entirely written in Maple.
http://www.math.rutgers.edu/~zeilberg/GT.html
Differential Gometry and General Relativity
An introduction to differential geometry and general relativity by Stefan Waner at Hofstra. This is an upper level undergraduate mathematics course which assumes a knowledge of calculus and some linear algebra.
http://people.hofstra.edu/faculty/Stefan_Waner/diff_geom/tc.html
Basic Concepts of Mathematics
This text by Elias Zakon helps the student complete the transition from purely manipulative to rigorous mathematics. Chapters cover Set Theory, the Real Numbers, and n-dimensional Geometry.
http://www.trillia.com/zakon1.html
Numerics - interactive
In this PDF book by Thomas Risse, basic numerical algorithms are presented and implemented in order to determine the precision of computation, to solve systems of linear equations, to evaluate elementary functions, to find zeros, to integrate and to solve
http://www.weblearn.hs-bremen.de/risse/MAI/docs/numerics.pdf
Geometric Asymptotics
This book by Guillemin and Sternberg includes the method of stationary phase, geometrical optics, quantization.
http://www.ams.org/online_bks/surv14/
Differential Algebra
Scans of Ritt's 1950 classic in PDF.
http://www.ams.org/online_bks/coll33/
Applied Cryptography
1996 CRC Handbook of Applied Cryptography by Menezes, van Oorschot and Vanstone in PDF.
http://cacr.math.uwaterloo.ca/hac/
Graph Theory
Hyperlinked PDF version of a book by Reinhard Diestel.
http://www.math.uni-hamburg.de/home/diestel/books/graph.theory/download.html
Homeomorphisms in Analysis
A survey by C. Goffman, T. Nishiura, D. Waterman in PDF. In particular, the effects of homeomorphic changes of domain on the analyticity of a function are studied.
http://www.ams.org/online_bks/surv54/
Finite Simple Groups
"The classification of the finite simple groups" by D. Gorenstein, R. Lyons, and R. Solomon in PDF.
http://www.ams.org/online_bks/surv40-1/
Matrices
The 1934 classic "Lectures on Matrices" by Wedderburn in scanned PDF.
http://www.ams.org/online_bks/coll17/
Stochastic Calculus
A fairly complete elementary introduction to the basics of stochastic integration with respect to continuous semimartingales by Alan Bain. All the theory usually needed for basic mathematical finance. Sixty pages in dvi, postscript, and pdf.
http://www.statslab.cam.ac.uk/~afrb2/
Linear Algebra
"Elementary Linear Algebra" by Keith Matthews. Lecture notes and solutions from 1991 in PDF or PostScript.
http://www.numbertheory.org/book/
Numerical Grid Generation
A book by Thompson, Warsi, and Mastin, previously published by Elsevier, in HTML.
http://www.erc.msstate.edu/publications/gridbook/
Wavelets
An Introduction to Wavelets by Amara Graps in HTML, PDF or Postscript.
http://www.amara.com/IEEEwave/IEEEwavelet.html
Algebraic Geometry
Various lecture notes by J.S. Milne.
http://www.jmilne.org/math/
Toposes, Triples and Theories
A book by Michael Barr and Charles Wells originally published by Springer Verlag.
http://www.cwru.edu/artsci/math/wells/pub/ttt.html
Dynamical Systems and Ergodic Theory
"Lectures on Dynamical Systems and Ergodic Theory" by Mark Pollicott and Michiko Yuri. Published by Cambridge University Press in 1998 (London Mathematical Society Students Texts, No. 40).
http://www.ma.man.ac.uk/~mp/book.html
Optimization
"Lecture Notes on Optimization" by Pravin Varaiya. This book is an introduction to mathematical programming, optimal control, and dynamic programming.
http://www-path.eecs.berkeley.edu/~varaiya/papers_ps.dir/NOO.pdf