""Biorthogonal Systems of Functions; Application of Biorthogonal Systems of Functions to the Theory of Integral Equations"" is a book written by Anna Johnson Pell and first published in 1911. The book is divided into two parts. The first part covers the topic of biorthogonal systems of functions, which are sets of two functions that are orthogonal to each other with respect to a given inner product. The author explains the properties and applications of biorthogonal systems of functions in detail, including their use in solving differential equations and in Fourier analysis.The second part of the book focuses on the application of biorthogonal systems of functions to the theory of integral equations. The author discusses the use of biorthogonal systems of functions in solving integral equations, which are equations that involve an unknown function as an integral. The author provides numerous examples and applications of biorthogonal systems of functions in integral equations, including the solution of boundary value problems and the study of singular integral equations.Overall, ""Biorthogonal Systems of Functions; Application of Biorthogonal Systems of Functions to the Theory of Integral Equations"" is a comprehensive and thorough treatment of the topic of biorthogonal systems of functions and their applications in integral equations. It is a valuable resource for mathematicians and scientists interested in these topics.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world's literature in affordable, high quality, modern editions, that are true to their original work.