Programmatically define elements of a matrix

Question

Gaetano Pavone 2020-7-7

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/561182-programmatically-define-elements-of-a-matrix

回答： Gaetano Pavone 2020-7-8

I have the following code:

cellnumber=6;
Vtype=4;
r=500;
H=500;
d=0.5*r;
nodes = [0 0 r 0 -r 0 sqrt(2)*r/2 -sqrt(2)*r/2 -sqrt(2)*r/2 sqrt(2)*r/2    
         0 0 0 r 0 -r sqrt(2)*r/2 sqrt(2)*r/2 -sqrt(2)*r/2 -sqrt(2)*r/2   
         H-d H 0 0 0 0 2*H-d 2*H-d 2*H-d 2*H-d];
totalnodes=size(nodes,2)+(cellnumber-1)*(size(nodes,2)-Vtype);
nodestotal=zeros(3,totalnodes);
for i=1:size(nodes,2)
    nodestotal(:,i)=nodes(:,i);
    for ii=size(nodes,2)+1:size(nodes,2)-Vtype:totalnodes
        nodestotal(1,ii)=nodes(1,1);
        nodestotal(2,ii)=nodes(2,1);
        nodestotal(3,ii)=?????????;
        for jj=size(nodes,2)+2:size(nodes,2)-Vtype:totalnodes
        nodestotal(1,jj)=nodes(1,2);
        nodestotal(2,jj)=nodes(2,2);
        nodestotal(3,jj)=?????????;
        end
    end
end

I would like to assign specific values to specific elements of nodestotal (indicated as ?????????) in for loop. In particular such values are:

nodestotal(3,11)=3*H-2*d          nodestotal(3,12)=3*H-*d
nodestotal(3,17)=5*H-3*d         nodestotal(3,18)=5*H-2*d
nodestotal(3,23)=7*H-4*d         nodestotal(3,24)=7*H-3*d
nodestotal(3,29)=9*H-5*d         nodestotal(3,30)=9*H-4*d
nodestotal(3,35)=11*H-6*d       nodestotal(3,36)=11*H-5*d

How can I do this?

Notice that cellnumber can vary.

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Answer 1

Gaetano Pavone 2020-7-8

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/561182-programmatically-define-elements-of-a-matrix#answer_462830

在 MATLAB Online 中打开

This is the solution:

for i=1:size(nodes,2)
    nodestotal(:,i)=nodes(:,i);
    index1=(size(nodes,2)+1:size(nodes,2)-Vtype:totalnodes);
    index2=(size(nodes,2)+2:size(nodes,2)-Vtype:totalnodes);
    for ii=size(nodes,2)+1:size(nodes,2)-Vtype:totalnodes
        nodestotal(1,ii)=nodes(1,1);
        nodestotal(2,ii)=nodes(2,1);
        idx1=find(index1==ii);
        nodestotal(3,ii)=((2*idx1)+1)*H-(idx1+1)*d;
        for jj=size(nodes,2)+2:size(nodes,2)-Vtype:totalnodes
            nodestotal(1,jj)=nodes(1,2);
            nodestotal(2,jj)=nodes(2,2);
            idx2=find(index2==jj);
            nodestotal(3,jj)=((2*idx2)+1)*H-idx2*d; 
        end
    end
end