 <code><a href="https://rdrr.io/pkg/fda/man/fdPar.html" class="external-link">fda::fdPar</a></code>.
Default value is NULL, in this case the smoothing parameter is chosen
by minimizing the generalized cross-validation (GCV)
criterion over the grid of values given by the argument.
See details on how smoothing parameters work.</p></dd>


<dt>lambda_grid</dt>
<dd><p>A vector of non-negative real numbers.
If <code>lambda</code> is provided as a single number, this argument is ignored.
If <code>lambda</code> is 