What is ind2sub

Question

Varun Nair 2021-7-19

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/882003-what-is-ind2sub

编辑： Walter Roberson 2021-7-23

This is the code where I had doubt on the syntax of ind2sub

%Parameters
A=0.01; %Wb is the unit of A
B=0.001; %H is the unit of Inductance
I =(0:1:2);        %row!
theta=(0:1:45).';    %column!
T = - A .* I .* cosd(theta) + B .* I.^2 .* sind(2*theta);
surf(I, theta, T)
xlabel('I'); ylabel('theta'); zlabel('Torque')
[maxT, idx] = max(T(:));
[r,c] = ind2sub(size(T), idx);
best_theta = theta(r);
best_I = I(c);
fprintf('best torque is %g at theta = %g and I = %g\n', maxT, best_theta, best_I);

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Answer 1

Star Strider 2021-7-20

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/882003-what-is-ind2sub#answer_750183

编辑：Walter Roberson 2021-7-23

在 MATLAB Online 中打开

MATLAB uses linear indexing for arrays, however many arrays are also referred to by subscripts into the rows, columns, and additional dimensions. The ind2sub function converts the linear indices into subscripts.

In this example:

[maxT, idx] = max(T(:));
[r,c] = ind2sub(size(T), idx);

the ind2sub call takes linear index ‘idx’ and converts it to the appropriate subscripts into matrix ‘T’. (It appears to be completely appropriate here.)

See the documentation section on Matrix Indexing for an extended discussion.

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