Try this (edited)
hold off
sumvec1 = [];sum = 0;
for n = 10:100
width = ((3 - 0)/n) ;
for c = 0:n
base1 = (width) * c- width ;
height = sqrt((base1 +1));
sum = sum + (width * height);
end
sumvec1 =[ sumvec1 sum];
end
figure;
i = 1:length(sumvec1);
scatter(i,sumvec1)
