why ismember() does not return correct result

Hello, I have an original matrix M ( Nx3 ) and another one mat ( Kx3 ). I want to have access to the indicies of rows of the original matrix, M, where the rows of the matrix mat also exist in matrix M. My code is:

idx = find(ismember(M, mat, "rows"))

While most of the rows of mat are correctly returned some rows do not. The common theme is that all of them have the third element equal (1.6).

The array mat:

Rows of array M: ( the row [-2.5 1.65 1.6] exists in the array ! )

Is this a floating point problem ?

Thanks

[Dyuman Joshi]

"Is this a floating point problem?"

Yes.

Also, experiment with the 2nd output of ismembertol.

Answer 1

[Star Strider]

They may have very small values that are not shown, especially if they are calculated.

Using the ismembertol function will likely do what you want.