Check a numeric vector, a matrix or an array of data values for consistency with the number of argument values.
ycheck(y, n)A numeric vector, matrix, or 3D array, with first dimension size
n.
The number of argument values for smoothing.
Argument y is returned if it checks out, converted to a one-column
matrix if the input was a numeric vector.
smooth.basis1,
smooth.monotone,
smooth.pos,
smooth.monotone,
smooth.surp