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Three preconditioners for solving boundary hypersingular integral
equations of the first kind are proposed. The first and the second
preconditioners are based on circulant operators. The third is a
hybrid of iterative substructuring techniques and circulant
operators. Although his class of preconditioners are composition
of circulant operators but we have shown that the condition number
of the third preconditioner does not exceed the condition number
of two preconditioners. Numerical results are included.
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