horzcat-error in subs for certain values

Hi everyone,

has anyone an idea on the following problem? I tried to create a minimal example of the problem. But in any more simple form the error does not show up. I wanted to do some matrix algebra and find eigensolutions that match a certain condition. For this i wrote:

syms c a alpha;

A = [ ...
    1 , 2*a + 40/2.23; ...
    0 , 1 ...
    ];

B = [ ...
    1 , 0; ...
    -2/50 , 1 ...
    ];

C = [ ...
    1 , c + (2*a+40+c)/cos(2*alpha); ...
    0 , 1 ...
    ];

D = B*C*B*A;

zr = sqrt(4-(D(1,1)+D(2,2))^2)/(2*D(2,1))-3.15;
z = (D(1,1)-D(2,2))/(2*D(2,1));

laenge = 19;
winkel = 13;

kante = double(solve(subs(zr,[a, alpha],[ laenge , winkel * (pi/180)]) , c));

q = 1/complex(subs( z , [a,alpha,c] , [laenge,winkel*(pi/180),kante] ),opt)

Running this code, i will get a solution without problems. But if i change the variable 'winkel' a little to 13.2 it results in the error

'Error using horzcat. CAT arguments dimensions are not consistent.'

which is pretty weird for me. I was thinking whether my equations maybe don't have solutions for these parameters, but i solved it with the same parameters in mathematica without any problems. Anyone has an idea what i did wrong?

Thanks for your help.

Regards

[Jan]

Please post the complete error message, which contain a hint to the corresponding line also!

[Walter Roberson]

Also, please show size() of all variables that appear in the line that is giving the error.

Answer 1

[Benjamin]

Hi everyone,

I added the complete error message, but the hint about the size of the variables brought the solution. The variable 'kante' had two solutions after solving the given equation. In Mathematica i considered this by choosing one of the solutions. Here I didn't. Now I do and it works fine.

Thanks!