why eq says they are not equal

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Nuchto
Nuchto 2012-7-19
I have two equal vectors a = b. When I check for equality:
y = eq(a, b)
find(y==0)
I get most of values, meaning they are NOT equal.
What would be the reason for this?
N.
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Jan
Jan 2012-7-22
@Nuchto: Is your problem solved?

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采纳的回答

Muruganandham Subramanian
编辑：Walter Roberson 2012-7-22
Hi Nuchto,
Check this below link:
http://www.mathworks.in/help/techdoc/ref/eq.html
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Nuchto
Nuchto 2012-7-19
I have checked the help, but it didn't answer to my question.

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更多回答（2 个）

Jan
Jan 2012-7-19
编辑：Jan 2012-7-19
To compare two vectors use:
r = isequal(a, b)
or to find the difference between vectors (or other arrays) of the same size:
any(a - b)
Note, that the later replies FALSE even for ones(1,10) and ones(1,1).
If you only assume, that the vectors have equal values, check a - b and note, that the limited precision of the type double leads to effects like:
03. - 0.2 ~= 0.1
Then check "almost equal" by:
limit = eps(max(max(abs(a(:)), abs(b(:)))));
% or: eps(max(abs(a(:)), abs(b(:))));
% or: the same times 10
a_eq_b = isequal(size(a), size(b)) & all(abs(a - b) < limit);
The choise of the limit depends on the physical meaning of the variables. There is no unique definition to distinguish measurement noise from noise caused by numerical artifacts for a tiny values.
Walter Roberson
Walter Roberson 2012-7-19

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