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In applied mathematics, the Kelvin functions ber''ν''(''x'') and bei''ν''(''x'') are the real and imaginary parts, respectively, of : where ''x'' is real, and , is the νth order Bessel function of the first kind. Similarly, the functions Kerν(''x'') and Keiν(''x'') are the real and imaginary parts, respectively, of : where is the νth order modified Bessel function of the second kind. These functions are named after William Thomson, 1st Baron Kelvin. While the Kelvin functions are defined as the real and imaginary parts of Bessel functions with ''x'' taken to be real, the functions can be analytically continued for complex arguments With the exception of Ber''n''(''x'') and Bei''n''(''x'') for integral ''n'', the Kelvin functions have a branch point at ''x'' = 0. Below, is the Gamma function and is the Digamma function. == ber(''x'') == For integers ''n'', ber''n''(''x'') has the series expansion : where is the Gamma function. The special case ber0(''x''), commonly denoted as just ber(''x''), has the series expansion : and asymptotic series :, where : : : 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Kelvin functions」の詳細全文を読む スポンサード リンク
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