Approximation theory lies at the cross-roads of pure and applied mathematics. It includes a wide spectrum of areas ranging from abstract problems of real, complex, and functional analysis to direct applications in engineering and industry. Correspondingly, the methods used in approximation theory vary widely and are related to analysis, operator theory, harmonic analysis, quantum calculus, algorithms, numerical analysis, and probability theory, only to mention some.

The focus of the present special issue is on the interaction between approximation theory and numerical analysis. For this, we are inviting authors to contribute both research articles and reviews highlighting achievements, new insights, and applications of approximation theory and numerical analysis. Interdisciplinary papers related to both subjects are of primary interest in this respect. The works containing conjectures, open problems, and/or numerical experiments will also be considered provided that they are based on solid theoretical backgrounds. Potential topics include, but are not limited to:

• Classical approximation theory including approximation by polynomials, rational functions, and positive linear operators
• Approximation in complex domains
• Approximation by operators based on the q-integers
• Approximation in abstract spaces
• Statistical approximation methods
• Spline approximation
• Numerical algorithms related to approximation procedures
• Numerical methods and computational issues in approximation
• Applications of approximation theory to other disciplines

Before submission authors should carefully read over the journal’s Author Guidelines, which are located at http://www.hindawi.com/journals/aaa/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/submit/journals/aaa/appx/ according to the following timetable: