Index exceeds the number of array elements (1)

1 次查看（过去 30 天）
Jonas Freiheit
Jonas Freiheit 2020-9-9
评论： Jonas Freiheit 2020-9-10
%When I try to perform a row interchange for 'b' vector It tells me it exceeds the no of array elements. This is an attempt to perform partial pivoting for matrix A and vector b separately.
Thanks
A = [1 2 3;4 2 -1; 3 2 3];
b = [1; 3; 2];
k = 1;
A = pivoting(A,k)
function [A, b, flag] = pivoting(A, b, k)
n = size(A,1);
flag = 0;
for k=1:n-1
[big, i]=max(abs(A(k:n,k)))
ipr=i+k-1
if ipr~=k
A([k,ipr],:)=A([ipr,k],:)
b([k,ipr])=b([ipr,k])
end
end
end

请先登录，再回答此问题。

采纳的回答

Kojiro Saito
Kojiro Saito 2020-9-9
It's because you're trying to manipulate b in line,
b([k,ipr])=b([ipr,k])
but, you're inputting as follows.
k = 1;
A = pivoting(A,k)
so, in function pivoting, b (second input variable) is scalar (1).
You just need to input three variables.
% A = pivoting(A,k)
A = pivoting(A,b,k)
  9 个评论
显示 7更早的评论
Kojiro Saito
Kojiro Saito 2020-9-10
It's not possible only changing the bold text code because the funtion pivoting requires three inputs, so you need to modify input variables so that it allows two inputs.
Jonas Freiheit
Jonas Freiheit 2020-9-10
Alright that makes sense,
Thanks for the help Kojiro!

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 Matrix Indexing 的更多信息

标签

产品


版本

R2020a

Community Treasure Hunt

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

Start Hunting!

Translated by