{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,28]],"date-time":"2025-10-28T03:12:02Z","timestamp":1761621122793},"reference-count":33,"publisher":"World Scientific Pub Co Pte Lt","issue":"04","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Open Syst. Inf. Dyn."],"published-print":{"date-parts":[[2012,12]]},"abstract":"<jats:p>We develop a general theory of almost Hadamard matrices. These are by definition the matrices H \u2208 M<jats:sub>N<\/jats:sub>(\u211d) having the property that [Formula: see text] is orthogonal, and is a local maximum of the 1-norm on O (N). Our study includes a detailed discussion of the circulant case (H<jats:sub>ij<\/jats:sub>= \u03b3<jats:sub>j-i<\/jats:sub>) and of the two-entry case (H<jats:sub>ij<\/jats:sub>\u2208 {x, y}), with the construction of several families of examples, and some 1-norm computations.<\/jats:p>","DOI":"10.1142\/s1230161212500242","type":"journal-article","created":{"date-parts":[[2012,12,20]],"date-time":"2012-12-20T12:21:22Z","timestamp":1356006082000},"page":"1250024","source":"Crossref","is-referenced-by-count":16,"title":["Almost Hadamard Matrices: General Theory and Examples"],"prefix":"10.1142","volume":"19","author":[{"given":"Teodor","family":"Banica","sequence":"first","affiliation":[{"name":"Department of Mathematics, Cergy-Pontoise University, 95000 Cergy\u2013Pontoise, France"}]},{"given":"Ion","family":"Nechita","sequence":"additional","affiliation":[{"name":"CNRS, Laboratoire de Physique Th\u00e9orique, IRSAMC, Universit\u00e9 de Toulouse, UPS, 31062, Toulouse, France"}]},{"given":"Karol","family":"\u017byczkowski","sequence":"additional","affiliation":[{"name":"Institute of Physics, Jagiellonian University, Cracow and Center for Theoretical Physics, Polish Academy of Sciences, Warsaw, Poland"}]}],"member":"219","published-online":{"date-parts":[[2012,12,20]]},"reference":[{"key":"rf1","doi-asserted-by":"publisher","DOI":"10.1007\/978-3-540-73074-3_23"},{"key":"rf2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jfa.2004.11.002"},{"key":"rf4","doi-asserted-by":"publisher","DOI":"10.1016\/j.jfa.2009.04.013"},{"key":"rf5","doi-asserted-by":"publisher","DOI":"10.1512\/iumj.2010.59.3926"},{"key":"rf6","doi-asserted-by":"publisher","DOI":"10.1016\/j.jcta.2010.11.015"},{"key":"rf7","doi-asserted-by":"publisher","DOI":"10.1142\/S0129167X11007343"},{"key":"rf8","first-page":"1","volume":"48","author":"Bengtsson I.","year":"2007","journal-title":"J. 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