Issue with matrix combination - error with sin and cos in matrix

Question

Tea Arrigoni 2017-12-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/372912-issue-with-matrix-combination-error-with-sin-and-cos-in-matrix

评论： Walter Roberson 2017-12-14

采纳的回答： Walter Roberson

在 MATLAB Online 中打开

Hi,

I have a following situation and I am not sure how to solve it.

FiA=-10:20:170
FiFm=-60:10:170
FiF=Fifm+FiA/3
COSF=Cos(FiF)
SINF=Sin(FiF)

I have a variable (angle) FiA that goes in deg from -10 until 170 with a step od 20.

Than I have variable FiF that is equal to variable Fifm+FiA/3 and the variable Fifm is also in deg from -60 until 170 with the step of 20.

And this part I manage to generate but the problem starts when I want to write down all possibilities of matrix that have the following variable. For example:

F=[1 0 0: 0 cofFiF - sinFif: 0 sinFif cosFif]

Then I get the error. When I write down the sinus and cosinus i can get all kind of combination but if I put them i matrix it gives me error.

Do you know maybe why?

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Answer 1

Walter Roberson 2017-12-14

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https://ww2.mathworks.cn/matlabcentral/answers/372912-issue-with-matrix-combination-error-with-sin-and-cos-in-matrix#answer_296199

在 MATLAB Online 中打开

FiA = -10:20:170;
FiFm = -60:10:170;
[gFiA, gFiFm] = ndgrid(FiA, FiFm);   %you want all combinations
gFiF = gFiFm + gFiA / 3;
COSF = cosd(gFiF);   %cosd and sind because you are working in degrees!
SINF = sind(gFiF);
F = arrayfun( @(sinFif, cosFif) [1 0 0; 0 cosFif -sinFif; 0 sinFif cosFif], SINF, COSF, 'uniform', 0);

The result will be a 10 x 24 cell array, in which each entry will be the rotation matrix for one Fia paired with one FiFm.

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Tea Arrigoni 2017-12-14

I need to add another variable that if dependent on these two. FiRm=-60:20:90

FiR=FiRm+7FiA/9 - FiF/9 + 2FiA*FiF/810

Its Matrix looks like this

R=[cosFiR - sinFir 0; sinFir cosFir 0 ; 0 0 1]

I tried to enter another variable in ndgrid but then everything goes wrong. Can you help on this issue? Thank you in advance

Walter Roberson 2017-12-14

在 MATLAB Online 中打开

FiA = -10:20:170;
FiFm = -60:10:170;
FiRm=-60:20:90;
[gFiA, gFiFm, gFiRm] = ndgrid(FiA, FiFm, FiRm];
gFiR = gFiRm + gFiA * (7/9) - gFiF / 9 + FiA .* FiF .* (2/810);
gcosFiR = cosd(gFiR);
gsinFiR = sind(gFir);
F = arrayfun( @(sinFir, cosFir) [cosFir -sinFif 0; sinFir cosFir 0; 0 0 1], gsinFir, gcosFir, 'uniform', 0);