Matrix Dimensions do not agree?

Question

Michael Jacobson 2018-5-9

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编辑： Stephen23 2018-5-10

Trying to figure out why this for loop isn't working. Both fz and lsFX are 1x7 arrays, so I don't get why I'm getting the error matrix dimensions must agree

lsFX = zeros(1,7);
fz = 0.2e+03:0.2e+03:1.4e+03;
sr = -0.26:0.001:0.26;
for i=1:7
lsFX(1,i) = fz.*D.*sin(C.*atan((B.*(sr+.045)-E.*(B.*(sr+.045)...
            -atan(B.*(sr+.045))))))-400;
end

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Answer 1

Geoff Hayes 2018-5-9

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https://ww2.mathworks.cn/matlabcentral/answers/399955-matrix-dimensions-do-not-agree#answer_319453

在 MATLAB Online 中打开

Michael - but sr is

sr = -0.26:0.001:0.26;

which is 1x521 which is the size of

 sin(C.*atan((B.*(sr+.045)-E.*(B.*(sr+.045)...
            -atan(B.*(sr+.045))))))-400

So when you are then multiplying that result by fz which is the 1x7...and so the error message makes sense.

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Geoff Hayes 2018-5-10

Michael - so you want to multiply each of the seven values in fz against all of the elements in sr? Could you not transpose fz to get a 7x1 matrix and then multiply that by the sr, the 1x521, to get a 7x521 result?

Michael Jacobson 2018-5-10

Yes! I had actually realized this earlier before I saw your post Geoff. I guess I was stuck thinking one dimensionally, but thankfully I was looking at some homework that refreshed my memory on matrix operations.

I also got rid of the loop and my plot is exactly as I want it now. Thank you for your answers sir !

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