Hello I would to figure out how to add poles into matrix from a for loop

I am designing a band pass filter and I need to take the roots of the low pass filter roots and store them. Can you please help me with this.

sp2 = roots(Gain_den);
sp = sp2(real(sp2)<0)
%sp=[1.0000 + 0.0000i  -0.2471 - 0.9660i   1.0000 + 0.0000i]
for k = 1:N_Stages
poles=[1 sp(k) 1]
p1=roots(poles)
end
I  had an idea coding it like this:
sp2 = roots(Gain_den);
sp = sp2(real(sp2)<0)
%sp=[1.0000 + 0.0000i  -0.2471 - 0.9660i   1.0000 + 0.0000i]
for k = 1:N_Stages
poles(k)=[1 sp(k) 1]
p1=roots(poles(k))
end

I had gotten this error when attempting to do it this way.

Unable to perform assignment because the left and right sides have a different number

of elements.

[darova]

You want to assign 3 values

It's impossible poles(k) has only 1 place ( for one value )

Answer 1

[Sai Sri Pathuri]

In the code,

poles(k)=[1 sp(k) 1]

you are assigning a row vector of size 1x3 to poles(k) with size 1x1. The error is due to mismatch between sizes.