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Degree of approximation to functions in a normed space. (English) Zbl 0945.42001
Let $$A$$ be a lower triangular nonnegative matrix and let $$\{t_n\}$$ be the sequence of $$A$$-transforms of the sequence of partial sums of the Fourier series of a $$2\pi$$-periodic function $$f$$. Here, the authors study the degree of approximation of $$f$$ in the Hölder metric by the sequence $$\{t_n\}$$. The theorems proved in this paper generalize some existing results in the field.

##### MSC:
 42A10 Trigonometric approximation 41A25 Rate of convergence, degree of approximation
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