IrregFunData:
3 observations of 1-dimensional support on 5 different argvals (3 - 5 per curve).

@argvals: List of 3
 $ : int [1:5] 1 2 3 4 5
  [list output truncated]

@X: List of 3
 $ : int [1:5] 1 2 3 4 5
  [list output truncated]
