Organize data as vector matrix and do calculation ?

Question

Yu-Chen 2013-5-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/77437-organize-data-as-vector-matrix-and-do-calculation

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

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Andrei Bobrov 2013-5-30

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/77437-organize-data-as-vector-matrix-and-do-calculation#answer_87087

编辑：Andrei Bobrov 2013-5-30

在 MATLAB Online 中打开

[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));

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

Iman Ansari 2013-5-30

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/77437-organize-data-as-vector-matrix-and-do-calculation#answer_87086

在 MATLAB Online 中打开

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

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 3

David Sanchez 2013-5-30

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/77437-organize-data-as-vector-matrix-and-do-calculation#answer_87089

在 MATLAB Online 中打开

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