clear

%%
np = 40;
f = @(x) 0.95*sin(2*pi*x);         
t = linspace(0, 1, np);
y = f(t);                            % values at nodes
plot(t, y, '.-')
hold on 
S = spinterp(t, y);
t1 = linspace(0, 1, 3*np);
sp = S(t1);
plot(t1, sp)
xlabel('x') 
ylabel('f(x)')
title('Function and cubic spline interpolant')
legend('function', 'spline interpolation')
grid on