comparing floating point numbers

Dear all,

I have two arrays A and B consisting of floating point numbers. The size of array A is [104,1] and B is [641,1]. I want to compare each element of A with every element of B.

[A]=[0
     2.527947992282320e-04
     1.809924379782077e-04
     ....
    ]
[B]=[0
     0.005
     0.010
     0.015
     .....
    ]

Kindly help me.

Thanks in advance.

[Image Analyst]

What does "compare" mean to you? Do you want to check for "equality"? Do you want to know which is greater or lesser? Do you want to know the distance (difference) between corresponding (or all) elements from each other? Please define "compare".

See the FAQ for info that will help you: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

Answer 1

[KSSV]

Read about ismemebrtol

[Abhinav Srivastava]

I am using MATLAB version 2013. Here this tool is not present.

Answer 2

[A Mackie]

A-B'

will generate a 104x641 matrix where each row is a value of A minus each individual value of B.

The ' operator takes the transpose of the vector B, allowing you to use implicit expansion. This will only work with later versions of MATLAB I believe.

[Guillaume]

In case B contains complex numbers using .' (plain transpose) would be safer than ' (which is the conjugate transpose).

In earlier versions of matlab (pre R2016b), you'd use bsxfun instead of implicit expansion

bsxfun(@minus, A, B.')

[Abhinav Srivastava]

I tried above two options but they didn't worked. I have to compare elements of A with B and group them within intervals present in B. The intervals in B can be interpreted as B = 0:0.01:1;

[Guillaume]

but they didn't worked

The bsxfun version is guaranteed to work (as long as you have enough memory to store the result). Now, it may not give the result you expected but that's because you've not explained clearly what you want.

I have to compare elements of A with B and group them within intervals present in B

So, are you trying to find the at which k index of B the value A(i) is between B(k) and B(k+1)?

[Abhinav Srivastava]

Yes I am trying to find index of k of B for which A(i) lies between B(k) and B(k+1). I think for that we need to check whether A(i) lies between B(k) and B(k+1)

[Guillaume]

"Yes I am trying to find index..."

Then I have answered that...

Answer 3

[Guillaume]

If you're trying to find at which k index of B the value A(i) is between B(k) and B(k+1), then:

[~, idx] = histc(A, B)  %in R2013. Newer versions of matlab have much better functions for that