pol_modal

 POL_MODAL  recursive construction of modal basis function 
            formula (2.3.31), pag. 82, CHQZ2
   [etak]=pol_modal(k,lk,lkm2)
            called by plot_modal

 Input: k = polynomial degree
        lk = character expression of L_k(x)
        lkm2 = character expression of L_{k-2}(x)

 Output: etak = character expression of \eta_k(x)

 Reference: CHQZ2 = C. Canuto, M.Y. Hussaini, A. Quarteroni, T.A. Zang,
                    "Spectral Methods. Fundamentals in Single Domains"
                    Springer Verlag, Berlin Heidelberg New York, 2006.

0001 function [etak]=pol_modal(k,lk,lkm2)
0002 % POL_MODAL  recursive construction of modal basis function
0003 %            formula (2.3.31), pag. 82, CHQZ2
0004 %   [etak]=pol_modal(k,lk,lkm2)
0005 %            called by plot_modal
0006 %
0007 % Input: k = polynomial degree
0008 %        lk = character expression of L_k(x)
0009 %        lkm2 = character expression of L_{k-2}(x)
0010 %
0011     % Output: etak = character expression of \eta_k(x)
0012 %
0013 % Reference: CHQZ2 = C. Canuto, M.Y. Hussaini, A. Quarteroni, T.A. Zang,
0014 %                    "Spectral Methods. Fundamentals in Single Domains"
0015 %                    Springer Verlag, Berlin Heidelberg New York, 2006.
0016 
0017 %   Written by Paola Gervasio
0018 %   $Date: 2007/04/01$
0019 
0020 
0021 ks=num2str(k);
0022 etak=['-1/sqrt(2*(2*',ks,'-1))*((',lk,')-(',lkm2,'))'];
0023 return
0024