Slight differences between NDVI calculated using Band math and the NDVI operator

Hi,

I’ve calculated the NDVI on a Sentinel-2 optical image (L2A) using both the Band math operator ((B8 - B4) / (B8 + B4)) and the operator found under the Optical menu in `SNAP.

But there were a slight differences in the results in certain areas (I’ve compared these results simple using a the difference operator with Band math).

I’m wondering which one I should use? and whether those very small differences are just due to the precision employed (number of decimals in the intensity)?

Thanks.

How big are the differences? Probably it is only a matter of precision.
Are they in an order of magnitude of 10^-6?

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Yes that’s what I thought (the difference is actually in the order of < 10e-7).
I just wanted to be sure that there’s no differences between the two methods.

I am calculating NDVI via band math in graph builder and I wanna just to be sure about what to insert in “Target band type” and “no-data value”: software automatically inserts “float32” and “0.0”. Is that correct? What about “band unit”?