how to write general code for generating points

Question

imola 2015-2-12

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编辑： imola 2015-2-17

Dear All,

I'm trying to write the following code in general way for dimension >=2, the code is

 m=4;
LB=[1 2 3 4]'; UB=[10 20 30 40]'; 
R=0.25*UB;
X=[];
for I=1:m
x1 = LB(I,:)+(UB(I,:)-LB(I,:))*rand(500,1);
idx = (x1 > LB(I,:)+R (I,:)) & (x1 < UB(I,:)-R(I,:));
X=[X x1];
x1(idx) = [];
end
plot(X(:,1),X(:,2), '.r');

can any one help me and give me an advice please.

thanks in advance.

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Answer 1

Sara 2015-2-12

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You can write the for loop in the following way:

for I=1:m
    x1 = LB(I)+(UB(I)-LB(I))*rand(500,1);
    X = [X x1];
    x1(x1 > LB(I)+R(I) & x1 < UB(I)-R(I)) = [];
end

It is not clear to me why X = [X x1]; is before the assignment x1(...) = []; though. You may have to switch those lines

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Sara 2015-2-12

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Of course you have the same figure: the X array contains all the x1 value and not only those selected with your criterion. That's why I suggested that you switch the lines: as they are, it makes no sense. Try this:

m=4;
LB=[1 2 3 4]'; UB=[10 20 30 40]';
R=0.25*UB;
X=[];
Xor = [];
for I=1:m
    x1 = LB(I)+(UB(I)-LB(I))*rand(500,1);
    Xor = [Xor;x1];
    x1(x1 > LB(I)+R(I) & x1 < UB(I)-R(I)) = [];
    X = [X;x1];
end
plot(Xor, 'ob');hold on % shows all the points initially calc
plot(X, '.r');  % shows only the selected values