b_rcs                   Basis for restricted cubic splines
b_rcs_prime             Derive first derivatives of RCS
cs_per                  Generate design matrix for periodic cubic
                        splines
plot_per_mod            Plotting function for periodic curves model
rcs_per                 Generate design matrix for periodic restricted
                        cubic spline
viral_east_mediteranean
                        Viral etiology, seasonality and severity of
                        hospitalized patients with severe acute
                        respiratory infections in the Eastern
                        Mediterranean Region, 2007-2014
