Not getting a finite answer

I am trying to excute following code and I am ending up getting infinity.

What I am trying to do is, compute signal to noise ratio for two different amplifications of M, 10 and 100. Final Signal 2 should include the contributions due to fluctuations of W, S and amplification factor (M). The output should be mean of final signal/standard deviation of final signal for M 10 and 100 separately. How do I separately obtain the data for M=10 and M=100?

W=1000; %Initial average excitation power
W1=W+rand(1,W)*10; %Power fluctuation
for M = [10 100] %Magnification factor
    W2=W1*M;
end
    for i=1:W2 %power fluctuation
end
S_i = 100; %Initial Signal
S=S_i+rand(1,S_i)*10; %Generate a set of multiple numbers for signal
for S_f=1:S %final signal
meanS=mean(S_f); %final signal 2
stdeviationS=std(S_f); %noise
SNRatio = mean(S_f)/std(S_f) %signal to noise ratio
end

[Walter Roberson]

for S_f=1:S %final signal
meanS=mean(S_f); %final signal 2
stdeviationS=std(S_f); %noise

Your for loop is over the integers 1:S. At each step you are taking the mean of the scalar integer loop variable, and the standard deviation of that scalar integer loop variable. The standard deviation of a scalar is always 0. The ratio of a positive value to 0 is infinite.

You are also overwriting outputs in each iteration of your first and third loops. Your second loop does nothing.

[Chanaka Navarathna]

Any suggestion to improve this code? Is there a way to carry the data generated from each loop and store and move to next step?

[Walter Roberson]

Sorry II cannot figure out the intent of the code based upon what is posted.

for ss = 1:whatever

result(ss) = calculted value

end

[Chanaka Navarathna]

[Chanaka Navarathna]

What I am trying to do is calculate the mean/standard deviation ratio of Sf1 and Sf2 separetely for two different values of M (10 and 100). W and Si also has to change within the loop.

[Walter Roberson]

num_W1 = length(W1);
Mvals = [10 100]; %Magnification factor
num_M = length(Mvals);
W2 = zeros(num_M, num_W1);
for M_idx = 1 : num_M
    M = Mvals(M_idx);
    W2(M_idx, :) = W1*M;
end

The above follows a general pattern that you should learn. The values you use in Mvals can be computed or assigned arbitrarily or created randomly as is appropriate for the situation. You then loop an index over the number of them that you have, and use the index to determine where to store the result of the computation.