equationsToMatrix output defaults to negative

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Adam Darcie 2021-5-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/827705-equationstomatrix-output-defaults-to-negative

I'm trying to use "equationsToMatrix" to put a system of symbolic equations into matrix form, but I'm getting the negative of what I want.

For example I have two vectors:

x1=[a1;b1;c1;d1];
x2=[a2;b2;c2;d2];

And I want to convert the following into the form x2=A*x1:

m = [a1*exp((R*pi*(alpha_ccw/2 + beta*1i))/2);
     b1*exp(-(R*pi*(alpha_ccw/2 + beta*1i))/2);
     c1*exp((R*pi*(alpha_cw/2 - beta*1i))/2);
     d1*exp(-(R*pi*(alpha_cw/2 - beta*1i))/2)]

So I use:

[Cprop_bottom,b] = equationsToMatrix(x2==m,x1)

I get the right answer but the negative. Essentially it says that both 'b' and 'Cprop_bottom' are negative so the solution is still true but not expected.

Am I doing something wrong? I could work around it by subsituting one of the 'b' output variables for a positive number and seeing if the result is negative, but I would prefer understand why the output defaults to negative to begin with.

Thanks in advance!