This article presents an application of a direct Trefftz method with domain
decomposition method to the two-dimensional potential problem. In the dire
ct Trefftz methods, regular T-complete functions satisfying the governing e
quations are taken as the weighting functions and then, the boundary integr
al equations are derived from the weighted residual expressions of the gove
rning equations. Since the T-complete functions are regular, the final equa
tions are also regular and therefore, much simpler than the ordinary bounda
ry element methods employing the singular fundamental solutions. Their comp
utational accuracy, however, is dependent on the condition number of the co
efficient matrices of the algebraic system of equations. So, for improving
the accuracy, we introduce the domain decomposition method to the direct Tr
efftz methods. The present method is applied to the two-dimensional potenti
al problem in order to confirm the validity. (C) 1999 Elsevier Science Ltd.
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