I am trying to plot for binary entropy

Question

Sam17 2018-1-31

评论： yair mazal 2021-3-17

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);

yair mazal 2021-3-17

Obviously you also miss the "2" in the second call to the log function. You're using log in the base of 10.

Answer 1

Walter Roberson 2018-1-31

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.