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| function [x,D]=fdper(N,order,pts);
% build equispaced grid on [-1,1], and
% pts points finite diference matrix for N mesh points
% for periodic domains
% $$$ N=10
% $$$ order=1
% $$$ pts=9
x=linspace(-1,1,N+1)';
x=x(1:end-1);
h=x(2)-x(1);
% subroutine for finite difference weights
W=ufdwt(h,pts,order);
t=(pts+1)/2;
R=zeros(1,N); R([end-t+2:end,1:t])=W(t,:);
C=zeros(1,N); C([t:-1:1,end:-1:end-t+2])=W(t,:);
D=toeplitz(C,R);
|
