sum(W)==1 used in a function does not work with the exact number

I have used "if sum(W)==1" in a function and the function does not work as it should. If I change it to "sum(W)<=1" it starts to work.

I have checked multiple times sum(W) is in fact equal to 1. I have tried several iterations e.g. increasing the value of W to more than 1 OR using "sum(W)>=1" In all iterations the conclusion is that something is getting lost in summation process and MATLAB thinks the sum is smaller than 1.

So my question what do I need to do for MATLAB to see that the sum of W is in fact 1 (and not less than 1).

The code (that works)is as follows:

function RARV=RARvariance1(A,B,C,D,E,F,G,H,W)

T=length(A); %Time period, the same for all assets

SW=sum(W);

    if SW<=1

    DD=[A-mean(A), B-mean(B), C-mean(C), D-mean(D), E-mean(E), F-mean(F), G-mean(G), H-mean(H)]; %Temporal, needed for covariances
    Cov=DD'*DD/T;

    V=W(1,:)*Cov*W(1,:)';

    %Portfolio expected returns
    ER=[mean(A), mean(B), mean(C), mean(D), mean(E), mean(F), mean(G), mean(H)]*W(1,:)';

    %(Negative) risk adjusted return
    RARV=-(ER)/sqrt(V); %Change V to sqrt(V) for semi-standard deviation
    else

   end

 *I need the code to work with SW==1 *

Thanks

[Image Analyst]

This should have been continued from your duplicate question. What is the value for W?

[Andrew]

W =[0.150000000000000 0.150000000000000 0.200000000000000 0.100000000000000 0.100000000000000 0.100000000000000 0.100000000000000 0.100000000000000]

which is exactly equal to 1

Answer 1

[Image Analyst]

Please read the FAQ: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

[Andrew]

Thank you very much. I tried the suggestion and it worked. It was a big help. I could not have guessed it. Thanks again.