do_csplines.m

辛普森方法

%do_csplines.m
KC = 1; dy0 = 2; dyN = 2; % with specified 1st derivatives on boundary
x = [0 1 2 3]; y = [0 1 4 5];
xi = x(1)+[0:200]*(x(end)-x(1))/200; %intermediate points
[yi,S] = cspline(x,y,xi,KC,dy0,dyN); % %cubic spline interpolation
clf, plot(x,y,'ko',xi,yi,'k:')
yi = spline(x,[dy0 y dyN],xi); %for comparison with MATLAB built-in ftn
hold on, pause, plot(x,y,'ro',xi,yi,'r:')
yi = spline(x,y,xi); %for comparison with MATLAB built-in ftn
pause, plot(x,y,'bo',xi,yi,'b')
KC = 3; [yi,S] = cspline(x,y,xi,KC);% with the 2nd derivatives extrapolated
pause, plot(x,y,'ko',xi,yi,'k')