using find function

im having a problem to find the correct value that i desire. im trying to plot graph for beamwidth for uniform array. but, the problem is that when i use the find function to find the angles which has -3dB gain, there is an error. so, i rounded up the -3dB angles to make it easy to use the find function. then, the rounded is not accrurate and consist some undesired value. example: p=-3.0041 -3.2098 -3.2000. I rounded up the value and it makes the value to become p= -3 -3 -3. hence, it contains some undesired value and makes it complicate to plot the graph. can anyone help to overcome this problem.

Answer 1

[Grzegorz Knor]

If I understand you correctly, try to round your vector roughly this way:

round(p*100)/100

or use find something like that:

find(abs(p-3)<0.001)

[Kugen Raj]

hi grzegorz,

Thanks for your suggestion. I tried as your showed here. But, I still cannot overcome the problem.

Y=sum(y);

YY=abs(Y);

p=20*log10(YY/max(YY));%normalized power in dB.

P=nearest(p);

PP=find(abs(P-3)<0.0001);

if size(PP)==[1,0];

bw(count2)=0;

else

bw(count2)=PP(1,2)-PP(1,1);

end

I'm still finding if there is any other alternative way to overcome this issue.

Answer 2

[Walter Roberson]

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