|
The neper (unit symbol Np) is a logarithmic unit for ratios of measurements of physical field and power quantities, such as gain and loss of electronic signals. The unit's name is derived from the name of John Napier, the inventor of logarithms. As is the case for the decibel and bel, the neper is a unit of the International System of Quantities (ISQ), but not part of the International System of Units (SI), but it is accepted for use alongside the SI.〔Bureau International des Poids et Mesures (2006), (The International System of Units (SI) Brochure, 8th edition ), pp 127-128.〕 ==Definition== Like the decibel, the neper is a unit in a logarithmic scale. While the bel uses the decadic (base-10) logarithm to compute ratios, the neper uses the natural logarithm, based on Euler's number (''e'' ≈ 2.71828). The value of a ratio in nepers is given by : where and are the values of interest, and ''ln'' is the natural logarithm. In the ISQ, the neper is defined as 1 Np = 1. 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「neper」の詳細全文を読む スポンサード リンク
|