Predict method for kernel regression. Evaluates the fitted regression function at a set of evaluation/test points
# S3 method for fk_regression
predict(object, xtest = NULL, ...)
vector of fitted/predicted values of the regression function.
an object of class fk_regression, output from the function of the same name.
(optional) vector of evaluation/test points. If omitted then the fitted values at the original sample are returned.
(optional) further arguments passed to or from other methods.