How to improve the code for vector calculation
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clear all
clc
NG=3;
B_area=rand(12,3);
P=rand(1,12)
P1=P(1:3);P2=P(4:6);P3=P(7:9);P4=P(10:12);
B_area1=B_area((1:3),:);
B_area2=B_area((4:6),:);
B_area3=B_area((7:9),:);
B_area4=B_area((10:12),:);
for i=1:NG
for j=1:NG
PL_area1(j)=P1(i).*B_area1(i,j).*P1(j);
PL_area2(j)=P2(i).*B_area2(i,j).*P2(j);
PL_area3(j)=P3(i).*B_area3(i,j).*P3(j);
PL_area4(j)=P4(i).*B_area4(i,j).*P4(j);
end
eval(['PL_area1' num2str(i) '=(PL_area1)']);
eval(['PL_area2' num2str(i) '=(PL_area2)']);
eval(['PL_area3' num2str(i) '=(PL_area3)']);
eval(['PL_area4' num2str(i) '=(PL_area4)']);
end
PL_area1=sum(PL_area11(:,:)+PL_area12(:,:)+PL_area13(:,:));
PL_area2=sum(PL_area21(:,:)+PL_area22(:,:)+PL_area23(:,:));
PL_area3=sum(PL_area31(:,:)+PL_area32(:,:)+PL_area33(:,:));
PL_area4=sum(PL_area41(:,:)+PL_area42(:,:)+PL_area43(:,:));
PL=[PL_area1 PL_area2 PL_area3 PL_area4]
回答（2 个）
Andrei Bobrov
2013-6-13
B = rand(12,3);
P = rand(1,12);
Ba = permute(reshape(B,3,4,[]),[1 3 2]);
Pn = reshape(P,3,1,[]);
Pa = bsxfun(@times,Pn,reshape(Pn,1,3,[])).*Ba;
PL = sum(reshape(Pa,[],4));
Iain
2013-6-13
Inner looop can be replaced by:
PL_area4=P4(i).*B_area4(i,:).*P4(:); etc.
The outer loop cannot be replaced unless you can formulate your mathematics into a matrix form.
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2013-6-13
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