Magnitude (mathematics) their magnitudes is called a norm. A vector space endowed with a norm, such as the Euclidean space, is called a normed vector space. Not all vector spaces are normed. In a pseudo-Euclidean space, the magnitude of a vector is the value of the quadratic form for that vector. When comparing magnitudes, a logarithmic scale is often used. Examples include the loudness of a sound (measured in decibels), the brightness of a star, and the Richter scale of earthquake intensity. Logarithmic magnitudes can be negative. It is not meaningful to simply add or subtract them. Orders of magnitude denote differences
Richter magnitude scale corrections, in that for distances less than 200 kilometers the attenuation is strongly affected by the structure and properties of the regional geology. When Richter presented the resulting scale in 1935 he called it (at the suggestion of Harry Wood) simply a "magnitude" scale. "Richter magnitude" appears to have originated when Perry Byerly told the press that the scale was Richter's, and "should be referred to as such." In 1956 Gutenberg and Richter, while still referring to "magnitude scale", labelled it "local magnitude", with the symbol , to distinguish it from two other scales they had developed, the surface wave