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Uzair Khan
Uzair Khan 2019-5-27
评论： Uzair Khan 2019-5-28
In the 3rd for loop , xloc(k) and yloc(k) are both vectors of length 6. And xp and yp are vectors of length 30 . If done alone the subtraction returns an error but here it doesn't. I wanna know what's so special here that it doesn't return an error?
if true
% xloc = [1,7,8,17,22,27] ;
yloc = [28,18,16,2,10,8] ;
V = [3,7,4,5,2,6] ;
best_loc_x = 31 ;
best_loc_y = 31 ;
min_cost = 1e+6 ;
anotherx = [] ;
anothery = [] ;
C = [] ;
for xp = 1:30
for yp = 1:30
for k = 1:6
d(k) = sqrt((xloc(k)-xp).^2+(yloc(k)-yp).^2) ;
cost(k) = d(k)*V(k);
end
loc_cost(xp,yp) = sum(cost) ;
if loc_cost(xp,yp) < min_cost
best_loc_x = xp;
best_loc_y = yp;
min_cost = loc_cost(xp,yp);
elseif (loc_cost(xp,yp)-min_cost) <=1
anotherx = [anotherx,xp] ;
anothery = [anothery,yp];
C = [C,loc_cost(xp,yp)];
end
end
end
end
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dpb
dpb 2019-5-27
编辑：dpb 2019-5-27
'Tis OK, but it makes more likely you'll get responses when make it easier for the folks to tryto help... :)
Do you see what's going on now w/ the Answer to help?
Uzair Khan
Uzair Khan 2019-5-27
No haven't really spent much time. So what about this question?

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采纳的回答

Walter Roberson
Walter Roberson 2019-5-27
for xp = 1:30 %so xp is a scalar
for yp = 1:30 %so yp is a scalar
for k = 1:6 %so k is a scalar
d(k) = sqrt((xloc(k)-xp).^2+(yloc(k)-yp).^2) ;
vector indexed at a scalar gives a scalar, so xloc(k) is a scalar and yloc(k) is a scalar. You subtract the scalars xp and yp from them, giving scalars for the sub-expressions. You square, add, square-root, giving a scalar output, which you store in a scalar location. No problem.
for xp = 1:30
does not make xp a vector of 30 elements: it tells MATLAB to iterate making xp hold each of the values 1:30 in turn, so at any one time xp is a scalar.
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Walter Roberson
Walter Roberson 2019-5-28
If you start from the beginning of a vector and count 1 for the first element, 2 for the second element, and so on, then d(k) refers to the content of the element for which the count is the same as the value k. For example d(7) is the seventh element. It is not the first seven elements together, just the one.

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dpb
dpb 2019-5-27
The key is line 17...

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