generate unit vectors based on matrix size

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Nitish Reddy Kotkur
Nitish Reddy Kotkur 2019-10-16
评论： Nitish Reddy Kotkur 2019-10-17
function [] = lanczos(A, m)
A = readmatrix('output1.txt','Whitespace',' []');
[n,k] = size(A);
V = zeros(k,k);
%V(:,2) = rand(k,1);
V(:,2)=[1 0 0 0 0 0 0 0 0 0 0]';
the v(:,2) is assigned based on matrix size ,which i did manually.But i need it to be created automaticaly based on matrix size.
for suppose if matrix is of size 5*5 then V(:,2)=[1 0 0 0 0]
if matrix is of size 7*7 then V(:,2)=[1 0 0 0 0 0 0]
if matrix is of size 100*100 then V(:,2)=[1 0 0 0 0........] i can't hand write such long vector so i need it to be generated automaticaly based on matrix size.

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James Tursa
James Tursa 2019-10-16
编辑：James Tursa 2019-10-16
Why not just V(1,2) = 1;
Or if you really need to explicitly set those 0’s then start with V(:,2) = 0; followed by the above.
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Steven Lord
Steven Lord 2019-10-16
The variables v (lower-case) and V (upper-case) are two different variables.
v = 'abracadabra';
V = 1:5;
whos
In the example above whos shows that v and V have different sizes, bytes, and classes.

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