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Output System
I'm having a problem of underdand the reason of the output of a system.

Hi guys,

Can anyone here explain me what are the reasons that the output of the following system is always zero?

A = [-0.2,0.0,0.0;0.0,-0.3,0.0;0.0,0.0,-0.7];
B = [0.0;0.0;2.5];
C = [0.0,2.6,0.0];
D = [0.0];

I tried to simulate in matlab:
[Y,X]=dstep(A,B,C,D,1,100);
stairs(Y);

Thanks in advance!

1 out of 1 members thought this post was helpful...

Hello Thiago,

Your D-matrix is zero, so there is no direct throughput from input to output, i.e. any non-zero output has to come from the states of the system.

>Can anyone here explain me what are the reasons that the
>output of the following system is always zero?
>
>A = [-0.2,0.0,0.0;0.0,-0.3,0.0;0.0,0.0,-0.7];
>B = [0.0;0.0;2.5];
>C = [0.0,2.6,0.0];
>D = [0.0];

<snip>

Your input-matrix B only has a non-zero element on Row 3, i.e. the input only directly affects the third state. The state matrix A is diagonal, so that the three states do not affect each other.

Your output matrix C only has a non-zero element in the second column, i.e. the output is only affected by the second state. However, since A is diagonal and B is only non-zero in its third row, the second state is not affected by the third state or the input, i.e. it always stays zero. Thus, the output also always stays zero.

Hope this helps.