I am trying to plot for binary entropy

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Sam17
Sam17 on 31 Jan 2018
Commented: yair mazal on 17 Mar 2021
I am trying to plot binary entropy and the value of entropy is coming as NaN but, it shouldn't be NaN, it should be 0.
Here's my code:
%Question No 1
%H(p) versus probability of binary logic 1 (p)
p= 0:0.5:1
h= p.*(abs(log2(p)))+ (1-p).*(abs(log(1-p)))
plot(p,h);
  1 Comment
yair mazal
yair mazal on 17 Mar 2021
Obviously you also miss the "2" in the second call to the log function. You're using log in the base of 10.

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Answers (1)

Walter Roberson
Walter Roberson on 31 Jan 2018
If your equations are correct then nan is the correct answer for p values of 0 and p values of 1.
Suppose p = 0. Then log2(p) is -infinity. p.*log2(p) is 0 * -infinity which is nan.
For p=1 something similar takes place.

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