MATLAB Answers

Comparing two numbers by using IF in Matlab

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Jamal Ahmad
Jamal Ahmad 15 Oct 2014
답변: Image Analyst 15 Oct 2014
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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채택된 답변

Iain
Iain 15 Oct 2014
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

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추가 답변(2개)

Stephen Carter
Stephen Carter 15 Oct 2014
They are not equal:
>> format long
>> x
x =
2.511886431509580
>> y
y =
2.511900000000000

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Image Analyst
Image Analyst 15 Oct 2014
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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