How to eliminate Nan

Gliq=(R*T*((x(1)*log(x(1)))+(x(2)*log(x(2)))+(x(3)*log(x(3)))+(x(4)*log(x(4)))+(x(5)*log(x(5)))+(x(6)*log(x(6)))+(x(7)*log(x(7)))+(x(8)*log(x(8)))));
for x=[0.162071097716028  0  0.276531475376737  0  0.264268578570244  0.247172330667782  0.0276055958119857  0.0223509218572239];

This code produces NaNs because of taking the natural log of zeros.

Can somebody help me how to eliminate Nans?

[James Tursa]

What would you like to have happen for those spots? Replace the NaN's with something else? Delete the NaN's from the result (i.e., shrink the size of the result)? Or ...?

[shailesh pathak]

to eliminate those Nan's

Answer 1

[Star Strider]

One option:

x=[0.162071097716028  0  0.276531475376737  0  0.264268578570244  0.247172330667782  0.0276055958119857  0.0223509218572239];
x = x(x > 0);

[shailesh pathak]

This is not working

[Star Strider]

Try this:

R = 8.344172;
T = 273;
x=[0.162071097716028  0  0.276531475376737  0  0.264268578570244  0.247172330667782  0.0276055958119857  0.0223509218572239];
x = x(x>0);
Gliq = R*T*x*log(x(:));

Vectorisation is much more efficient.

[Image Analyst]

I'm having trouble following all those thousands of parentheses. But it looks like the RT is multiplying the sum of all the terms, so do you mean

Gliq = R*T*sum(x.*log(x));

[Star Strider]

That’s essentially it.

It uses ‘dot product’ (link) vector multiplication to multiply row vector ‘x’ by column vector ‘log(x(:))’.

Gliq = R*T*dot(x,log(x))

produces the same result.

Answer 2

[James Tursa]

result = the stuff you are currently doing
result(isnan(result)) = [];

[shailesh pathak]

Getting the same problem

[James Tursa]

"... This is not working ..." and "... Getting the same problem ..."

These comments do not help us since they give us no further detail into the issues you are having. Please show us your complete code, the current result you are getting, and then show us the result that you would like to get.