function isoeff
p1=1:1024;w1=p1/2;
p2=1:512;w2=p2.^(5/4) / 2.2;
p3=1:128;w3= 13 * (2.^(p3/20) - 1);
plot(p1,w1,p2,w2,p3,w3);
legend('Very good','Satisfactory','Poor');
xlabel('Number of processors used');
ylabel('Work load');