# What is a Gauss sign?

"A Method for Extraction of Bronchus Regions from 3D Chest X-ray CT Images by Analyzing Structural Features of the Bronchus" by Takayuki KITASAKA, Kensaku MORI, Jun-ichi HASEGAWA and Jun-ichiro TORIWAKI

and I run into a term I do not understand:

In equation (2), when we say "[] expresses the Gauss sign", what does it mean?

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You may want to add the title of the paper, and its bibliographic information... –  Arturo Magidin Feb 14 '12 at 5:12
Notation –  pedja Feb 14 '12 at 5:18
@pedja: seriously? Is that it? Gauss sign is just floor and ceiling functions? But then it must be either floor or ceiling, isn't it? Or is it a round function, where if the number is < 0.5, floor function is applied and vice versa? –  Karl Feb 14 '12 at 5:25
@J.M. Well, voxel coordinates I imagine would need integer-valued arguments, so I think the last line would be evidence this is the NINT function... –  anon Feb 14 '12 at 5:47
@J.M. I think pedja was just specifying what he meant. If there's good reason to believe this is a rounding function and these brackets are the rounding function attributed to Gauss with the same exact notation, then I think we have a match here. –  anon Feb 14 '12 at 6:03

per signum $[x]$ exprimemus integrum ipsa $x$ proxime minorem, ita ut $x-[x]$ semper fiat quantitas positiva intra limites $0$ et $1$ sita