清空筛选条件
清空筛选条件

Cannot get factorial loop to work! Do not know command...

1 次查看（过去 30 天）
S
S 2014-2-9
回答： Roger Stafford 2014-2-9
The question is evaluate the following series: 1^2 + 2^2 +3^2 ... + 100^2. The answer is suppose to be 338350 but the only code i can get working is
a=[1:100] b=2; y=a.^b for y=1:length(a) end
which gives me each columns value, but does not add it up to value 338350! I have tried everything for a whole week please help :(

请先登录，再回答此问题。

回答（2 个）

Mischa Kim
Mischa Kim 2014-2-9
编辑：Mischa Kim 2014-2-9
Use
a = [1:100];
b = 2;
y = 0;
for ii = 1:length(a)
y = y + a(ii)^b;
end
display(y);
Your sum, y, needs to be inside the loop to be updated. Alternatively, you can make use of MATLAB's matrix operations
y = sum([1:100].^2);
  3 个评论
显示 1更早的评论
John D'Errico
John D'Errico 2014-2-9
编辑：John D'Errico 2014-2-9
Noe that the internal brackets [] are slightly bad, in the sense that they may make your code slightly less efficient. Use () there instead, so
y = sum((1:100).^2);
is better. Not a major issue, but one to remember. If you don't really need brackets, which will result in an extra function call overhead that was never needed, don't use them. Use parens instead. I'm pretty sure that mlint flags this issue.

请先登录，再进行评论。

Roger Stafford
Roger Stafford 2014-2-9
Yet another way is:
n = 100;
y = n*(n+1)*(2*n+1)/6;

类别

在 Help Center 和 File Exchange 中查找有关 Loops and Conditional Statements 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by