% Indexing exercise 1 answer

thisyear = 2010;
years = [1900:thisyear];
B=1969;
ii=years>=1969;
age = zeros(size(years));
age(ii) = years(ii)-B;
iu=years>=1987&years<=1990;
plot(years,age,'bo')
hold on
plot(years(iu),age(iu),'ro')