trend1d - Fit a [weighted] [robust] polynomial [or Fourier] model for y = f(x) to xy[w] data. trend1d -F < xymrw > -N [ f ] n _ model [ r ] [ xy [ w ] file ] [ -C condition _# ] [ -H [ nrec ] ] [ -I [ confidence _ level ] ] [ -V ] [ -W ] [ -: ] [ -bi [ s ][ n ] ] [ -bo [ s ] ] trend1d reads x,y [and w] values from the first two [three] columns on standard input [or xy [ w ] file ] and fits a regression model y = f(x) + e by [weighted] least squares. ... E.g., a robust quadratic model is -N 3 r . ...