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Variable assigned in NaN in loop iteration
Summing 2D vectordifferent sized bins in matlabMatlab: How I can make this transformation on the matrix A? (part 2)Basic file I/O in MatlabFaster way of implementing-To assign label for every pixelPlot specific jumps in value range of a matrixShannon's entropy for non-equiprobable occurence of symbols in a blockHow to compute double sum in Matlab where upper bound of second sum is lower bound of first sum?Ignore NaN when detrending 3-d arrayUsing Matlab's lsqcurvefit to Calculate Infinite Relaxation Spectrum
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I am trying to calculate Entropy manually and my variable to store the result gets a NaN value at every iteration. I have the following code snippet in a matlab function -
entropy = 0.0;
%Calculating entropy...
for i = 1:size(freq_norm)
val = freq_norm(i);
val_log = log2(val);
mul = val * val_log;
entropy = entropy - mul;
disp(['VALUE: ',num2str(entropy)]);
end
Here freq_norm is a vector which consists of values which sum to 1 (like a pdf).
I have the exact same snippet in another part of the program which goes 1:6 values and works perfectly.
I have also printed out all val, val_log, mul values and none of them are NaN and print as expected. mul contains values which are approximately about -0.05.
Any help appreciated. Thanks!
matlab
asked Mar 23 at 13:27
Nalin KambojNalin Kamboj
299
add a comment |
I am trying to calculate Entropy manually and my variable to store the result gets a NaN value at every iteration. I have the following code snippet in a matlab function -
entropy = 0.0;
%Calculating entropy...
for i = 1:size(freq_norm)
val = freq_norm(i);
val_log = log2(val);
mul = val * val_log;
entropy = entropy - mul;
disp(['VALUE: ',num2str(entropy)]);
end
Here freq_norm is a vector which consists of values which sum to 1 (like a pdf).
I have the exact same snippet in another part of the program which goes 1:6 values and works perfectly.
I have also printed out all val, val_log, mul values and none of them are NaN and print as expected. mul contains values which are approximately about -0.05.
Any help appreciated. Thanks!
matlab
asked Mar 23 at 13:27
Nalin KambojNalin Kamboj
299
What is the value of yourfreq_normvector? I triedfreq_norm = 0.2 * ones(1, 5);and didn't get any NaNs.
– LarrySnyder610
Mar 23 at 13:33
2
Iffreq_normcontains a 0, the log will be -Inf, which you then multiply by 0 to get NaN. You need to skip the zeros to compute entropy.
– Cris Luengo
Mar 23 at 13:34
Turns out it did contain a 0. It has 256 values and I missed checking a couple of them. Thanks!
– Nalin Kamboj
Mar 23 at 18:02
add a comment |
I am trying to calculate Entropy manually and my variable to store the result gets a NaN value at every iteration. I have the following code snippet in a matlab function -
entropy = 0.0;
%Calculating entropy...
for i = 1:size(freq_norm)
val = freq_norm(i);
val_log = log2(val);
mul = val * val_log;
entropy = entropy - mul;
disp(['VALUE: ',num2str(entropy)]);
end
Here freq_norm is a vector which consists of values which sum to 1 (like a pdf).
I have the exact same snippet in another part of the program which goes 1:6 values and works perfectly.
I have also printed out all val, val_log, mul values and none of them are NaN and print as expected. mul contains values which are approximately about -0.05.
Any help appreciated. Thanks!
matlab
asked Mar 23 at 13:27
Nalin KambojNalin Kamboj
299
I am trying to calculate Entropy manually and my variable to store the result gets a NaN value at every iteration. I have the following code snippet in a matlab function -
entropy = 0.0;
%Calculating entropy...
for i = 1:size(freq_norm)
val = freq_norm(i);
val_log = log2(val);
mul = val * val_log;
entropy = entropy - mul;
disp(['VALUE: ',num2str(entropy)]);
end
Here freq_norm is a vector which consists of values which sum to 1 (like a pdf).
I have the exact same snippet in another part of the program which goes 1:6 values and works perfectly.
I have also printed out all val, val_log, mul values and none of them are NaN and print as expected. mul contains values which are approximately about -0.05.
Any help appreciated. Thanks!
matlab
matlab
asked Mar 23 at 13:27
Nalin KambojNalin Kamboj
299
asked Mar 23 at 13:27
Nalin KambojNalin Kamboj
299
asked Mar 23 at 13:27
Nalin KambojNalin Kamboj
299
asked Mar 23 at 13:27
Nalin KambojNalin Kamboj
299
asked Mar 23 at 13:27
Nalin KambojNalin Kamboj
299
299
What is the value of yourfreq_normvector? I triedfreq_norm = 0.2 * ones(1, 5);and didn't get any NaNs.
– LarrySnyder610
Mar 23 at 13:33
2
Iffreq_normcontains a 0, the log will be -Inf, which you then multiply by 0 to get NaN. You need to skip the zeros to compute entropy.
– Cris Luengo
Mar 23 at 13:34
Turns out it did contain a 0. It has 256 values and I missed checking a couple of them. Thanks!
– Nalin Kamboj
Mar 23 at 18:02
add a comment |
What is the value of yourfreq_normvector? I triedfreq_norm = 0.2 * ones(1, 5);and didn't get any NaNs.
– LarrySnyder610
Mar 23 at 13:33
2
Iffreq_normcontains a 0, the log will be -Inf, which you then multiply by 0 to get NaN. You need to skip the zeros to compute entropy.
– Cris Luengo
Mar 23 at 13:34
Turns out it did contain a 0. It has 256 values and I missed checking a couple of them. Thanks!
– Nalin Kamboj
Mar 23 at 18:02
What is the value of your
freq_norm vector? I tried freq_norm = 0.2 * ones(1, 5); and didn't get any NaNs.– LarrySnyder610
Mar 23 at 13:33
What is the value of your
freq_norm vector? I tried freq_norm = 0.2 * ones(1, 5); and didn't get any NaNs.– LarrySnyder610
Mar 23 at 13:33
2
2
If
freq_norm contains a 0, the log will be -Inf, which you then multiply by 0 to get NaN. You need to skip the zeros to compute entropy.– Cris Luengo
Mar 23 at 13:34
If
freq_norm contains a 0, the log will be -Inf, which you then multiply by 0 to get NaN. You need to skip the zeros to compute entropy.– Cris Luengo
Mar 23 at 13:34
Turns out it did contain a 0. It has 256 values and I missed checking a couple of them. Thanks!
– Nalin Kamboj
Mar 23 at 18:02
Turns out it did contain a 0. It has 256 values and I missed checking a couple of them. Thanks!
– Nalin Kamboj
Mar 23 at 18:02
add a comment |
1 Answer
1
active
oldest
votes
The log2 function is returning NaN, probably because at some point you are trying to take the log of 0 (which is -Inf) and multiplying by 0.
See this example for reference.
answered Mar 23 at 13:34
medicine_manmedicine_man
27113
add a comment |
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The log2 function is returning NaN, probably because at some point you are trying to take the log of 0 (which is -Inf) and multiplying by 0.
See this example for reference.
answered Mar 23 at 13:34
medicine_manmedicine_man
27113
add a comment |
The log2 function is returning NaN, probably because at some point you are trying to take the log of 0 (which is -Inf) and multiplying by 0.
See this example for reference.
answered Mar 23 at 13:34
medicine_manmedicine_man
27113
add a comment |
The log2 function is returning NaN, probably because at some point you are trying to take the log of 0 (which is -Inf) and multiplying by 0.
See this example for reference.
answered Mar 23 at 13:34
medicine_manmedicine_man
27113
The log2 function is returning NaN, probably because at some point you are trying to take the log of 0 (which is -Inf) and multiplying by 0.
See this example for reference.
answered Mar 23 at 13:34
medicine_manmedicine_man
27113
answered Mar 23 at 13:34
medicine_manmedicine_man
27113
answered Mar 23 at 13:34
medicine_manmedicine_man
27113
answered Mar 23 at 13:34
medicine_manmedicine_man
27113
27113
add a comment |
add a comment |
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What is the value of your
freq_normvector? I triedfreq_norm = 0.2 * ones(1, 5);and didn't get any NaNs.– LarrySnyder610
Mar 23 at 13:33
2
If
freq_normcontains a 0, the log will be -Inf, which you then multiply by 0 to get NaN. You need to skip the zeros to compute entropy.– Cris Luengo
Mar 23 at 13:34
Turns out it did contain a 0. It has 256 values and I missed checking a couple of them. Thanks!
– Nalin Kamboj
Mar 23 at 18:02