How to check whether there is a particular element in a row vector?

Consider the row vector CR2 (matrix attached). I want to check whether any of its element is equal to 0.2. In this case CR2 actually contains 0.2 (position 57), but if I type sum(CR2==0.2) I get zero. Could you help me in fixing this? Thank you!

Answer 1

[Jan]

Inspect the difference between the 57th element and 0.2:

disp(CR2(57) - 0.2)

What do you get?

[Image Analyst]

I'm sure he does, and so do I, as I started you out with my code. Not sure what you want to do after that so I leave it for you to finish.

[Stella]

oo, I see, I get -5.5511e-17! Thank you!

Answer 2

[Image Analyst]

See the FAQ: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F So you can't just test for equality and you need to check for some tolerance or find the min. Jan's suggestion of looking at the min difference is a good idea. Follow that up with a call to min and be sure to get the second return argument:

absDiff = abs(CR2 - 0.2)
[minDifference, indexAtMin] = min(absDiff);
if minDifference < 0.0001  % or whatever tolerance you want
% and so on......

(I assume you were honest when you did not tag it as homework. I hope this wasn't your homework I just did for you, or now you might need to find another way to do it. It can be done with a for loop and an if test.)