计算系列的总和

Question

我需要计算这个系列的总和

我需要这样的输出：

If n = 3;

x = function_name(n)

我需要得到 x = 11.

If n = 5;

x = function_name(n)

我需要得到 x = 45.

我相信我需要一个 for 循环来迭代；但我发现很难迭代增量值本身。

Answer 1

我猜你想要 sum of the cumsum 的差异 d 的数字：

d = 2;
n = 5;

s  =  d:d:d*(n-1)
cs  = cumsum( [1 s] )
scs = sum(cs)

%// or as anonymous function

scsh = @(n,d) sum( cumsum( [1 d:d:d*(n-1)] ) )

---

scs =

    45

scsh(5,2) =

    45

无需循环！

Answer 2

inc=2;
sum=1;
next=1;

n=input('what is n?\n');

for i=2:n
    next=next+inc;
    sum=sum+next;
    inc=inc+2;
end

disp('sum is ');
disp(sum);

Answer 3

function Total = abc(n)

nth_term=1;
Total = 1 ;   


    for  d = 2:2:(2*(n-1))
         nth_term = nth_term + d;       
         Total =Total + nth_term;    

    end

end