t = 0:0.2:25
s1 = 0.1553567.*t.^6 - 2.0416.*t.^5 + 9.1837.*t.^4 - 14.829.*t.^3 - 1.3703.*t.^2 + 32.821.*t - 1.3155
s2 = 0.003980879.*t.^5 - 0.2247.*t.^4 + 4.8682.*t.^3 - 50.442.*t.^2 + 254.67.*t - 430.66
s3 = -0.073.*t.^2 + 6.1802.*t + 40.423


idx1 = []
idx2 = []
idx3 = []
for i = 1:length(t)
    if t(i) < 5
        idx1 = [idx1, 1];
        idx2 = [idx2, 0];
        idx3 = [idx3, 0];
    elseif t(i) < 15.4
        idx1 = [idx1, 0];
        idx2 = [idx2, 1];
        idx3 = [idx3, 0];
    else t(i) <= 25
        idx1 = [idx1, 0];
        idx2 = [idx2, 0];
        idx3 = [idx3, 1];
    end
end
hold on
plot(t(idx1),s1(idx1))
plot(t(idx2),s2(idx2))
plot(t(idx3),s3(idx3))
hold off