Hi, can you help me!!! I 've got a problem when i went to calculate this matrix:

A= [Aa  0;-Af*Ca  Af]

With

Aa=[-0.01320 0 0 9.8100 0 0 0 0;-0.08560 -0.9903 -241.7000 0 21.7500 0.9504 18.0800 -0.00073;-0.00017 0.0159 -0.9883 0 -0.4850 -0.0323 -3.3200 -0.10450;0 0 1 0 0 0 0 0;0 0 0 0 0 1 0 0;0.08420 0.8897 -3.0300 0 -164.6000 -4.2050 -28.0500 -0.59690;0 0 0 0 0 0 0 1;-0.02920 -0.1723 -5.0970 0 -2.8540 -0.4456 -430.5000 -2.15500];
Af=diag([-10 -10]);

[Bob Thompson]

What kind of problem are you getting?

[the cyclist]

Please add more detail to your question!

Describe the problem. Does MATLAB return an error? What is the full error message?

Or maybe you just get something unexpected. What did you get? Why do you think it is wrong.

We can't help if we don't fully understand what is going on with your code.

[yousra yahia]

Ca=[-0.05540 -0.6511 5.1620 0 112.2000 3.0360 152.9000 1.1390;-0.00804 -0.0850 0.2943 0 -2.9510 -0.0590 -26.5500 -0.1560];

[yousra yahia]

Af=diag([-10 -10]);
Ca=[-0.05540 -0.6511 5.1620 0 112.2000 3.0360 152.9000 1.1390;-0.00804 -0.0850 0.2943 0 -2.9510 -0.0590 -26.5500 -0.1560];
Aa=[-0.01320 0 0 9.8100 0 0 0 0;-0.08560 -0.9903 -241.7000 0 21.7500 0.9504 18.0800 -0.00073;-0.00017 0.0159 -0.9883 0 -0.4850 -0.0323 -3.3200 -0.10450;0 0 1 0 0 0 0 0;0 0 0 0 0 1 0 0;0.08420 0.8897 -3.0300 0 -164.6000 -4.2050 -28.0500 -0.59690;0 0 0 0 0 0 0 1;-0.02920 -0.1723 -5.0970 0 -2.8540 -0.4456 -430.5000 -2.15500];
A=[Aa 0;-Af.*Ca Af];

Error using horzcat
Dimensions of matrices being concatenated are not consistent.

Error in Matrice (line 4)
A=[Aa 0;-Af.*Ca Af];

[Walter Roberson]

http://www.mathworks.co.uk/matlabcentral/answers/43073-a-guide-to-tags

Answer 1

[James Tursa]

You need to tell MATLAB how many 0's are being concatenated in the upper right corner. E.g.,

A = [Aa  zeros(size(Aa,1),size(Af,2));-Af*Ca  Af];

[yousra yahia]

This answer did not give me a solution

[the cyclist]

This code, which is exactly what you posted (with a bit of reformatting), and James' correction, worked for me.

Af=diag([-10 -10]);

Ca=[-0.05540 -0.6511 5.1620 0 112.2000 3.0360 152.9000 1.1390;
    -0.00804 -0.0850 0.2943 0 -2.9510 -0.0590 -26.5500 -0.1560];

Aa=[-0.01320 0 0 9.8100 0 0 0 0;
    -0.08560 -0.9903 -241.7000 0 21.7500 0.9504 18.0800 -0.00073;
    -0.00017 0.0159 -0.9883 0 -0.4850 -0.0323 -3.3200 -0.10450;
    0 0 1 0 0 0 0 0;
    0 0 0 0 0 1 0 0;
    0.08420 0.8897 -3.0300 0 -164.6000 -4.2050 -28.0500 -0.59690;
    0 0 0 0 0 0 0 1;
    -0.02920 -0.1723 -5.0970 0 -2.8540 -0.4456 -430.5000 -2.15500];

A = [Aa  zeros(size(Aa,1),size(Af,2));-Af*Ca  Af];

Note that John changed

-Af.*Ca

to

-Af*Ca

to make it a matrix multiplication. Your code, which would do element-by-element multiplication would fail because you cannot do that between a 2x2 and a 2x8. Whether that type of multiplication is what you need is up to you to determine.

[yousra yahia]

Thank you, i got the result but i had an other problem :

Af=diag([-10 -10]) Da=[4.3970 33.4300; -0.4182 -1.1780] Ba=[0 0;6.8060 9.2750; -1.7700 -0.7986; 0 0;0 0; 6.1130 -42.0300; 0 0; -20.2700 -13.2900] B=[Ba -Af*Da]

>> Af=diag([-10 -10]) Da=[4.3970 33.4300; -0.4182 -1.1780] Ba=[0 0;6.8060 9.2750; -1.7700 -0.7986; 0 0;0 0; 6.1130 -42.0300; 0 0; -20.2700 -13.2900] B=[Ba -Af*Da]

Af =

   -10     0
     0   -10

Da =

    4.3970   33.4300
   -0.4182   -1.1780

Ba =

         0         0
    6.8060    9.2750
   -1.7700   -0.7986
         0         0
         0         0
    6.1130  -42.0300
         0         0
  -20.2700  -13.2900

Error using horzcat Dimensions of matrices being concatenated are not consistent.