6 papers
Improvement of conformal maps combined with the Sinc approximation for derivatives over infinite intervals
Tomoaki Okayama, Yuito Kuwashita, Ao Kondo
F. Stenger proposed efficient approximation formulas for derivatives over infinite intervals. These formulas were derived by combining the Sinc approximation with appropriate confo…
Relation between two Sinc-collocation methods for Volterra integral equations of the second kind and further improvement
Tomoaki Okayama
Stenger and Rashidinia--Zarebnia independently proposed two Sinc-collocation methods for Volterra integral equations of the second kind, but the relation between the methods has no…
Refinement of the theory and convergence of the Sinc convolution -- beyond Stenger's conjecture
Tomoaki Okayama
The Sinc convolution is an approximate formula for indefinite convolutions proposed by Stenger. The formula was derived based on the Sinc indefinite integration formula combined wi…
DE-Sinc approximation for unilateral rapidly decreasing functions and its computable error bound
Tomoaki Okayama
The Sinc approximation is highly effective for functions that decay rapidly at both ends of the real axis. For unilateral rapidly decreasing functions, which decay algebraically as…
Explicit error bounds of the SE and DE formulas for integrals with logarithmic and algebraic singularity
Tomoaki Okayama, Kosei Arakawa, Ryo Kamigaki +1
The single exponential (SE) and double exponential (DE) formulas are widely recognized as efficient quadrature formulas for evaluating integrals with endpoint singularity. For inte…
Improvement of Sinc-collocation methods for Volterra-Fredholm integral equations of the second kind and their theoretical analysis
Tomoaki Okayama
Sinc-collocation methods for Volterra-Fredholm integral equations of the second kind were proposed independently by multiple authors: by Shamloo et al. in 2012 and by Mesgarani and…