Costas array: Difference between revisions

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In mathematics, a '''Costas array''' can be regarded [[geometry|geometrically]] as a set of ''n'' points lying on the [[Square (geometry)|square]]s of a ''n''×''n'' [[checkerboard]], such that each row or column contains only one point, and that all of the ''n''(''n'' − 1)/2 [[displacement (vector)|displacement]] [[vector (geometric)|vector]]s between each pair of dots are distinct. This results in an ideal 'thumbtack' auto-[[ambiguity function]], making the arrays useful in applications such as [[sonar]] and [[radar]]. Costas arrays can be regarded as two-dimensional cousins of the one-dimensional [[Golomb ruler]] construction, and, as well as being of mathematical interest, have similar applications in [[experimental design]] and [[phased array]] radar engineering.
 
Costas arrays are named after [[John P. Costas (engineer)|John P. Costas]], who first wrote about them in a 1965 technical report. Independently, [[Edgar Gilbert]] also wrote about them in the same year, publishing what is now known as the logarithmic Welch method of constructing Costas arrays.<ref>{{citation
| last = Gilbert | first = E. N. | authorlink = Edgar Gilbert
| doi = 10.1137/1007035
| issue = 2
| journal = SIAM Review
| jstor = 2027267
| pages = 189–198
| title = Latin squares which contain no repeated digrams
| volume = 7
| year = 1965}}.<ref>[http://nanoexplanations.wordpress.com/2011/10/09/an-independent-discovery-of-costas-arrays/ An independent discovery of Costas arrays], Aaron Sterling, October 9, 2011.</ref>
 
==Numerical representation==
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Enumeration of known Costas arrays to order 200<ref name="JKB200"/>, order 500<ref><James K Beard, ''Costas array generator polynomials in finite fields'', 42nd Annual Conference on Information Sciences and Systems (CISS 2008), April 20, 2008, [https://doi.org/10.1109/CISS.2008.4558709| DOI: 10.1109/CISS.2008.455870]</ref> and to order 1030 <ref>http://jameskbeard.com/jameskbeard/Files.html#CostasArrays</ref>.
 
==Constructions==