yFit = gampredict (Parameters, X, Intercept) adds the intercept to the sum of the additive terms evaluated at each row of X and returns the $Nx1$ result. It is the prediction engine shared by ClassificationGAM and RegressionGAM, and it is not meant to be called directly.

• Parameters is a $1xP$ structure array of piecewise polynomials, as returned by gamtrain in the field of the same name.
• X is an $NxP$ numeric matrix with one column per additive term, and a count that does not match is an error. A model carrying interaction terms must therefore be given the augmented matrix, not the predictors alone. A missing value predicts NaN, since no term of the model is defined at it. A value outside the range the term was fitted over is extrapolated from the nearest piece, as ppval extrapolates.
• Intercept is the model’s constant term.
• Link, if given, selects what the additive prediction is mapped through: 0 returns it as it stands and 1 takes it as a log-odds, returning the $Nx2$ matrix of class probabilities whose second column is the logistic function of it. The default is 0.

See also: gamtrain, ClassificationGAM, RegressionGAM, fitcgam, fitrgam

Source Code: gampredict