Defining a matrix using empty parenthesis

2 次查看（过去 30 天）
Zena Assaad
Zena Assaad 2014-10-22
评论： Zena Assaad 2014-10-23
Hi all,
Just a small problem with notation. I have the following for loop:
G = [];
W = [];
W(1) = 77000;
for i = 1:29
G = [G, SFC*Thrust1(i)*(disp(i)/V1(i))]
W = [W(i+1), (W(i)-G(i))]
end
I am getting the following error:
Index exceeds matrix dimensions.
Error in fueloptimal (line 139)
W = [W(i+1), (W(i)-G(i))]
I need to define W(i+1) using the empty parenthesis before the 'for loop', i.e. W = [ ]. Have I done this correctly? Or is the issue coming from somewhere else?
Thanks in advance!

请先登录，再回答此问题。

采纳的回答

Image Analyst
Image Analyst 2014-10-22
The problem is not only W(i+1). It's W(i). Defining W = [], which is null, does not mean that there is a first element, element #1. There is no element W(1). Null means nothing, not even a first element that is null. So you can't append/prepend anything to it. You can append to W if it's null, but not to W(1) or any other specific index number because they're not there yet.
And of course on the ith iteration there is no (i+1)th element either, because you haven't gotten there yet. When i = 1, why do you expect that a W(2) exists already? It doesn't.
  3 个评论
显示 1更早的评论
Image Analyst
Image Analyst 2014-10-23
Oh, you're right - it is there. If you did that then there was no need to do W=[] just prior to it.
So the first time through your loop with i=1, you're doing W = [W(2), (W(1)-G(1))] but the problem is, on the first iteration there is no W2 yet!

请先登录，再进行评论。

更多回答（0 个）

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