I have a code that yields a solution similar to the desired output, and I don't know how to perfect this.
The code is as follows.
N = 4; % sampling period
for nB = -30:-1;
if rem(nB,N)==0
xnB(abs(nB)) = -(cos(.1*pi*nB)-(4*sin(.2*pi*nB)));
else
xnB(abs(nB)) = 0;
end
end
for nC = 1:30;
if rem(nC,N)==0
xnC(nC) = cos(.1*pi*nC)-(4*sin(.2*pi*nC));
else
xnC(nC) = 0;
end
end
nB = -30:-1;
nC = 1:30;
nD = 0;
xnD = 0;
plot(nA,xnA,nB,xnB,'r--o',nC,xnC,'r--o',nD,xnD,'r--o')
This produces something that is close, but not close enough for proper data recovery.
I have tried using an index that has the same length but simply starts at 1
but the output was even worse than this, though if that is a viable option please explain thoroughly, how it should be done.
I have tried running this in a single for-loop
with one if-statement
but there is a problem when the counter passes zero. What is a way around this that would allow me to avoid using two for-loops
? (I'm fairly confident that, solving this issue would increase the accuracy of my output enough to successfully recover the signal.)
EDIT/CLARIFICATION/ADD - 1
I do in fact want to evaluate the signal at the index of zero. The if-statement
cannot handle an index of zero which is an index that I'd prefer not to skip.
The goal of this code is to be able to sample a signal, and then I will build a code that will put it through a recovery filter.
EDIT/UPDATE - 2
nA = -30:.1:30; % n values for original function
xnA = cos(.1*pi*nA)-(4*sin(.2*pi*nA)); % original function
N = 4; % sampling period
n = -30:30;
xn = zeros(size(n));
xn(rem(n,N)==0) = -(cos(.1*pi*n)-(4*sin(.2*pi*n)));
plot(nA,xnA,n,xn,'r--o')
title('Original seq. x and Sampled seq. xp')
xlabel('n')
ylabel('x(n) and xp(n)')
legend('original','sampled');
This threw an error at the line xn(rem(n,N)==0) = -(cos(.1*pi*n)-(4*sin(.2*pi*n)));
which read: In an assignment A(I) = B, the number of elements in B and I must be the same. I have ran into this error before, but my previous encounters were usually the result of faulty looping. Could someone point out why it isn't working this time?
EDIT/Clarification - 3
N = 4; % sampling period
for nB = -30:30;
if rem(nB,N)==0
xnB(abs(nB)) = -(cos(.1*pi*nB)-(4*sin(.2*pi*nB)));
else
xnB(abs(nB)) = 0;
end
end
The error message resulting is as follows: Attempted to access xnB(0); index must be a positive integer or logical.
EDIT/SUCCESS - 4
After taking another look at the answers posted, I realized that the negative sign in front of the cos function wasn't supposed to be in the original coding.