Summation with for loops

Hi, I'm trying to plot the summation graph of y=1/(1+x)^2, so far my code is

x=[-10:10]

y=zeros(size(x))

for n=1:21

for k=1:11

terms= k.*(-x(n)).^(k-1)

y=y+terms

end

end

at the moment it is plotting a straight line but my friend believes this code is correct, any help is greatly appreciated.

Answer 1

[Star Strider]

I’m not certain what a ‘summation graph’ is.

One of these will probably do what you want:

x = -10:10;
y = zeros(size(x));
for n=1:21
    for k=1:11
        terms(n,k) =  k.*(-x(n)).^(k-1);
    end
end
row_cumsum = cumsum(terms);
col_cumsum = cumsum(terms,2);

row_sum = sum(terms);
col_sum = sum(terms,2);

figure
plot(row_cumsum)

figure
plot(col_cumsum)

figure
plot(row_sum)

figure
plot(col_sum)

Experiment to get the result you want.