Problem with indexing within a vector
3 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
I have two vectors, x and y. I would like to make third vector, z, which has the combined magnitude of x and y, i.e. sqrt(x.^2 + y.^2) but has the sign of whichever of x and y has the bigger individual magnitude. If the example below, z should be [-10.20 5.39 10.77 -10.44]. However I am incorrectly indexing the matrix bothVectorsTogether, so that it returns a 4x4 matrix instead of a 4x1 vector. What is the right way to index it? The "real" x and y have 950000 elements so I want to avoid looping through each row to identify the sign.
% Initialize example vectors
x = [-10 5 4 -10]';
y = [2 -2 10 -3]';
zMagnitude = sqrt(x.^2 + y.^2); % Size 4x1
% Find which has a bigger individual magnitude, x or y
[~, whichIsBigger] = max(abs([x y])'); % 1 if x is bigger, 2 if y is bigger
bothVectorsTogether = [x y];
zSign = sign(bothVectorsTogether(:, whichIsBigger)); % Size 4x4 not 4x1
z = zMagnitude.*zSign;
0 commentaires
Réponse acceptée
Azzi Abdelmalek
le 13 Mar 2013
Modifié(e) : Azzi Abdelmalek
le 13 Mar 2013
x = [-10 5 4 -10]';
y = [2 -2 10 -3]';
idx=abs(x)>abs(y);
s=y;
s(idx)=x(idx);
z=sqrt(x.^2 + y.^2).*sign(s)
Plus de réponses (0)
Voir également
Catégories
En savoir plus sur Matrix Indexing dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!