function g = gcvfctn(h, d, fc2, trS0, dof0)%GCVFCTN    Evaluate object function for generalized cross-validation.%%   GCVFCTN(h, d, fc2, trS0, dof0) returns the function values of the%   generalized cross-validation object function%%                     trace [ S0 + F' * diag(g.^2) * F ]%              G(h) = ---------------------------------- %                           ( dof0 + sum(g) )^2%%   where g = h^2 ./ (d + h^2) = 1 - d.^2 ./ (d + h^2). The argument h%   of the GCV function is the regularization parameter, and d is a%   column vector of eigenvalues (see GCVRIDGE for the meaning of the%   other symbols above). GCVFCTN is an auxiliary routine that is%   called by GCVRIDGE. The input arguments are defined in GCVRIDGE:%%        h:  regularization parameter,%        d:  column vector of eigenvalues of cov(X),%      fc2:  row sum of squared Fourier coefficients, fc2=sum(F.^2, 2),%     trS0:  trace(S0) = Frobenius norm of generic part of residual matrix,%     dof0:  degrees of freedom in estimate of residual covariance%            matrix when regularization parameter is set to zero  %   Adapted from GCVFUN in Per Christian Hansen's REGUTOOLS Toolbox.  filfac = (h^2) ./ (d + h^2);              g      = ( sum(filfac.^2 .* fc2) + trS0 ) / (dof0 + sum(filfac))^2;