Organize data as vector matrix and do calculation ?

1 Ansicht (letzte 30 Tage)
Yu-Chen
Yu-Chen am 30 Mai 2013
I want to organize the data returned by sph2cart as a matrix with vector element and all the element in matrix will perform some calculation(vector-vector or vector-scalar calculation) with a vector. Here is an example i achieve this however it's somewhat redundant, how could i make it more terse ? Thanks.
lightV = zeros(1, 1, 3);
lightV(1,1,1) = 0.5;
lightV(1,1,2) = 0.4;
lightV(1,1,3) = 0.7;
[Az El] = meshgrid(0:60:360, 0:15:90);
[x y z] = sph2cart(Az*pi/180, El*pi/180, 1);
refV = zeros(size(Az,1), size(Az,2), 3);
radius = zeros(size(Az,1), size(Az,2));
for i = 1:size(Az,1)
for j = 1:size(Az,2)
refV(i,j,1) = -x(i,j);
refV(i,j,2) = -y(i,j);
refV(i,j,3) = z(i,j);
radius(i,j) = dot(refV(i,j,:), lightV(1,1,:));
end
end

Akzeptierte Antwort

Andrei Bobrov
Andrei Bobrov am 30 Mai 2013
Bearbeitet: Andrei Bobrov am 30 Mai 2013
[Az, El] = meshgrid(0:60:360, 0:15:90);
[x, y, z] = sph2cart(Az*pi/180, El*pi/180, 1);
refV2 = cat(3,-x,-y,z);
lightV = [.5 .4 .7];
radius = sum(bsxfun(@times,refV,reshape(lightV,1,1,[])),3);
or
radius = reshape([-x(:), -y(:), z(:)]*lightV.',size(x));

Weitere Antworten (2)

Iman Ansari
Iman Ansari am 30 Mai 2013
lightV = zeros(1, 1, 3);
lightV(1,1,1) = 0.5;
lightV(1,1,2) = 0.4;
lightV(1,1,3) = 0.7;
[Az El] = meshgrid(0:60:360, 0:15:90);
[x y z] = sph2cart(Az*pi/180, El*pi/180, 1);
refV=cat(3,-x,-y,z);
radius= lightV(1,1,1)*-x+lightV(1,1,2)*-y+lightV(1,1,3)*z

David Sanchez
David Sanchez am 30 Mai 2013
a couple of changes:
% you know the values from the start and no need of 3D matrix
lightV = [.5 .4 .7];
[Az El] = meshgrid(0:60:360, 0:15:90);
[x y z] = sph2cart(Az*pi/180, El*pi/180, 1);
refV = zeros(size(Az,1), size(Az,2), 3);
radius = zeros(size(Az,1), size(Az,2));
for i = 1:size(Az,1)
for j = 1:size(Az,2)
refV(i,j,1) = -x(i,j);
refV(i,j,2) = -y(i,j);
refV(i,j,3) = z(i,j);
ref = reshape(refV(i,j,:),1,3); % reshape to 2D matrix
radius(i,j) = dot(ref, lightV(1,:));
end
end

Kategorien

Mehr zu Resizing and Reshaping Matrices finden Sie in Help Center und File Exchange

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by