Comparing two numbers by using IF in Matlab

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Jamal Ahmad
Jamal Ahmad 2014-10-15
回答： Image Analyst 2014-10-15
I want to compare two numbers (x, and y), if they are equal or not.
However, even if these two numbers are equal, if condition in Matlab does not recognize them as equal numbers.
How I can make if statement recognize these two numbers if they are equal?
x=10.^(0.1.*4);
y=2.5119;
if x == y
z=1
'equal'
else
z=2
'Not Equal'
end

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采纳的回答

Iain
Iain 2014-10-15
The code is correct.
The problem is that x - y is not precisely 0. The magnitude of the difference will be less than 1e-5
You have two options, define y to the 16th significant figure, or allow a tolerance like this:
if abs(x-y) < tolerance

更多回答（2 个）

Stephen Carter
Stephen Carter 2014-10-15
They are not equal:
>> format long
>> x
x =
2.511886431509580
>> y
y =
2.511900000000000
Image Analyst
Image Analyst 2014-10-15
See the FAQ for an explanation and some code to make it do what you want: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

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