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In coding theory, rank codes (also called Gabidulin codes) are non-binary〔Codes for which each input symbol is from a set of size greater than 2.〕 linear error-correcting codes over not Hamming but ''rank'' metric. They described a systematic way of building codes that could detect and correct multiple random ''rank'' errors. By adding redundancy with coding ''k''-symbol word to a ''n''-symbol word, a rank code can correct any errors of rank up to ''t'' = ⌊ (''d'' − 1) / 2 ⌋, where ''d'' is a code distance. As an erasure code, it can correct up to ''d'' − 1 known erasures. A rank code is an algebraic linear code over the finite field similar to Reed–Solomon code. The rank of the vector over is the maximum number of linearly independent components over . The rank distance between two vectors over is the rank of the difference of these vectors. The rank code corrects all errors with rank of the error vector not greater than ''t''. == Rank metric == Let — ''n''-dimensional vector space over the finite field , where is a power of a prime, is an integer and with is a base of the vector space over the field . Every element can be represented as . Hence, every vector over can be written as matrix: : ''Rank of the vector'' over the field is a rank of the corresponding matrix over the field denoted by . The set of all vectors is a space . The map ) defines a norm over and a ''rank metric'': : 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「Rank error-correcting code」の詳細全文を読む スポンサード リンク
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