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


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)?


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”?