  plerrx(n, xmin, xmax, y)
  ************************

  plerrx

  Draws a set of n horizontal error bars, the i'th error bar extending from
  xmin[i] to xmax[i] at y coordinate y[i]. The terminals of the error bar are
  of length equal to the minor tick length (settable using plsmin).

  n (PLINT, input): Number of error bars to draw.

  xmin (PLFLT *, input): Pointer to array with x coordinates of left-hand
  endpoint of error bars.

  xmax (PLFLT *, input): Pointer to array with x coordinates of right-hand
  endpoint of error bars.

  y (PLFLT *, input): Pointer to array with y coordinates of error bar.

