How do I extract each value from a column matrix and subsitute in a equation?

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Shiv Karpoor 2022-1-26

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评论： Shiv Karpoor 2022-1-26

Hello MATLAB Community,

I have a small problem with regards to for loop.

I am trying to use the for loop to solve an equation and store all the values from that particular equation, but I am facing a problem where the loop is considering all values of a matrix to solve it.

for example : a1 = (-25 : 25); a2 = (-25 : 25); a3 = (-25 : 25);

Now I use the combvec function the find all possible combinations

comb = (combvec(a1,a2,a3)); and then I say

phi = comb(1,:);

theta = comb(2,:);

psi = comb(3,:);

Now, I need to subsitute each value of phi, theta and psi (all values of column 1 of comb matrix) into the equation:

ROT = [(cos(phi)*cos(psi))-(cos(theta)*sin(phi)*sin(psi)) -(cos(phi)*sin(psi))-(cos(theta)*cos(psi)*sin(phi)) (sin(phi)*sin(theta));...

(cos(psi)*sin(phi))+(cos(phi)*cos(theta)*sin(psi)) (cos(phi)*cos(theta)*cos(psi)-sin(phi)*sin(psi)) -(cos(phi)*sin(theta));...

(sin(theta)*sin(psi)) (cos(psi)*sin(theta)) cos(theta)];

Similarly, for the next iteration I will consider all values of column 2 of comb matrix and so on, upto the last column of the comb matrix.

Can anyone please help me with any suggestions.

Thank you in advance!!

I really appreciate your help.

Kind regards,

Shiv

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Answer 1

Matt J 2022-1-26

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https://ww2.mathworks.cn/matlabcentral/answers/1636580-how-do-i-extract-each-value-from-a-column-matrix-and-subsitute-in-a-equation#answer_882205

编辑：Matt J 2022-1-26

在 MATLAB Online 中打开

Change all of your '*' operators to elementwise operator '.*'

res=@(z) reshape(z,1,1,[]);
phi = res( comb(1,:) );
theta = res( comb(2,:) );
psi = res( comb(3,:)  );
ROT = [(cos(phi).*cos(psi))-(cos(theta).*sin(phi).*sin(psi)) -(cos(phi).*sin(psi))-(cos(theta).*cos(psi).*sin(phi)) (sin(phi).*sin(theta));...
(cos(psi).*sin(phi))+(cos(phi).*cos(theta).*sin(psi)) (cos(phi).*cos(theta).*cos(psi)-sin(phi).*sin(psi)) -(cos(phi).*sin(theta));...
(sin(theta).*sin(psi)) (cos(psi).*sin(theta)) cos(theta)];