Please help...

Question

andy ganteng 2011-11-8

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/20611-please-help

I have function like this,

function knotident(x,nknot,rand)
clc;
[~,n]=size(x);
for i=1:n
    z=x(:,i);
    c=min(z);
    d=max(z);
    if nknot == 1
        t=random('unif',c,d,[rand,1]);
    else
        for g=1:nknot
            r=random('unif',c,d,[rand,1]);
            t(:,g)=r;
        end
        t=sort(t,2); 
    end
kgab(:,i)=t;
end

rand and nknot can be any number. now, i wanna save the result from the loop above for t in matrix with size (rand,nknot*n), but i don't know how to do that. in that syntax i use kgab(:,i)=t; but it cant work if nknot>1. Please help me...

thanks in advance

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andy ganteng 2011-11-8

aim sorry....i've edit my question...now, please help...

andy ganteng 2011-11-8

if nknot>1 then matlab said

??? Subscripted assignment dimension mismatch.

Error in ==> knotident at 20

kgab(:,i)=t;

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Answer 1

Jan 2011-11-8

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/20611-please-help#answer_27226

在 MATLAB Online 中打开

"kgab(:,i)=t;" does not work if t is a matrix.

I've clean up the source a little bit, most of all the repeated computations are move out of the loop:

function knotident(x, nknot, r)
n = size(x, 2);
dim  = [r, nknot];
minx = min(x, 1);
maxx = max(x, 1);
kgab = [r, n * nknot];  % Pre-allocate!
if nknot == 1
  for i = 1:n
    kgab(:, i) = random('unif', minx(i), maxx(i), dim);
  end
else  % knot > 1
  v = 1;
  for i = 1:n
    t = sort(random('unif', minx(i), maxx(i), dim), 2); 
    kgab(:, v:(v + nknot - 1)) = t;
    v = v + nknot;
  end
end