clear; clc; close all;

x = linspace(0, 4 * pi, 10);
y = sin(x) .* exp(-x / 5);

xq = linspace(0, 4 * pi, 100);
yq = interp1(x, y, xq, 'spline');

figure;
plot(x, y, 'o'); grid on; hold on;
plot(xq, yq, 'r--');
plot(xq, sin(xq) .* exp(-xq / 5), 'g:.');