invers matrix error calculate

Question

pablolama 2019-2-3

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/442942-invers-matrix-error-calculate

评论： John D'Errico 2019-2-3

OA=1.42
AB=4.3
BO=3.33
OO=6
alfa=linspace(19.7, -103, 14);
beta= [37.3648, 40.5764, 43.6511, 46.4267, 48.7411, 50.4573, 51.4816, 51.7706, 51.3269, 50.1884, 48.4165, 46.0853, 43.2749, 40.0669];
gamma= [-68.0355, -66.333, -63.8261, -60.6513, -56.9882, -53.0279, -48.9467, -44.8871, -40.9515, -37.2048, -33.6824, -30.3996, -27.3598, -24.5623]
J=[AB*sind(beta) BO*sind(gamma); AB*cosd(beta) BO*cosd(gamma)]
omega=(inv(J))*[OA*sind(alfa); OA*sind(alfa)]
disp(omega)

It calculates:

OA =
    1.4200
AB =
    4.3000
BO =
    3.3300
OO =
     6
gamma =
  -68.0355  -66.3330  -63.8261  -60.6513  -56.9882  -53.0279  -48.9467  -44.8871  -40.9515  -37.2048  -33.6824  -30.3996  -27.3598  -24.5623
J =
  Columns 1 through 16
    2.6096    2.7970    2.9681    3.1153    3.2325    3.3159    3.3644    3.3778    3.3571    3.3031    3.2164    3.0976    2.9476    2.7678   -3.0883   -3.0499
    3.4176    3.2660    3.1113    2.9639    2.8357    2.7376    2.6779    2.6609    2.6870    2.7531    2.8540    2.9824    3.1307    3.2908    1.2455    1.3367
  Columns 17 through 28
   -2.9885   -2.9026   -2.7924   -2.6604   -2.5111   -2.3500   -2.1825   -2.0135   -1.8468   -1.6851   -1.5304   -1.3842
    1.4689    1.6321    1.8142    2.0027    2.1870    2.3593    2.5150    2.6523    2.7710    2.8722    2.9575    3.0287
Error using inv
Matrix must be square.
Error in accelerazioniangolari (line 9)
omega=(

How can i solve the error, it calculates J not like 14 matrix, i think that is the problem. How can i fix it?

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John D'Errico 2019-2-3

编辑：John D'Errico 2019-2-3

https://www.mathworks.com/matlabcentral/answers/442898-how-to-find-the-inverse-of-a-6-2-matrix

pablolama 2019-2-3

在 MATLAB Online 中打开

But my matrix is 2x2

J=[AB*sind(beta) BO*sind(gamma); AB*cosd(beta) BO*cosd(gamma)]

When it calculates, it gives me

J =
  Columns 1 through 16
    2.6096    2.7970    2.9681    3.1153    3.2325    3.3159    3.3644    3.3778    3.3571    3.3031    3.2164    3.0976    2.9476    2.7678   -3.0883   -3.0499
    3.4176    3.2660    3.1113    2.9639    2.8357    2.7376    2.6779    2.6609    2.6870    2.7531    2.8540    2.9824    3.1307    3.2908    1.2455    1.3367
  Columns 17 through 28
   -2.9885   -2.9026   -2.7924   -2.6604   -2.5111   -2.3500   -2.1825   -2.0135   -1.8468   -1.6851   -1.5304   -1.3842
    1.4689    1.6321    1.8142    2.0027    2.187
    0    2.3593    2.5150    2.6523    2.7710    2.8722    2.9575    3.0287

So it it is no more a 2x2 and i can't calculate its inverse. How can i solve it?

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Answer 1

John D'Errico 2019-2-3

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/442942-invers-matrix-error-calculate#answer_359303

在 MATLAB Online 中打开

You cannot use inv on a 2x28 array. So either of these forms are equally valid:

omega=pinv(J)*[OA*sind(alfa); OA*sind(alfa)];
omega=J\[OA*sind(alfa); OA*sind(alfa)];

Neither is more technically coerrect, and you can take your free choice between which of infintely many solutions you want. The two options above are just two of the many possible.

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pablolama 2019-2-3

There is not a way to have 14 2x2 matrix when i calculate J?

John D'Errico 2019-2-3

在 MATLAB Online 中打开

You cannot assume that MATLAB will be smart enough to figure out what you want to do, when you try to do something completely unusual. Instead, MATLAB does what you tell it to do, and can do no more than that.

However, nothing stops you from using a loop. Loops are not the worst thing in the world. They are not that inefficient.

doc for

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