What Is The Lowest E-Value In Blast When Ncbi Rounds It Down To 0 (Zero)?

Question

[Andrzej Zielezinski]

Hello,

Just out of curiosity, an E-value of more significant hits in BLAST approaches 0, but cannot equal 0. In some cases when the E-value of a HSP is very low NCBI BLAST rounds it down to 0. What is the actual value (e.g. 1e-180?, 1e-1000?) of these E-values rounded to 0?

Answer 1

[Michael]

I think it is [1] 2.225074e-308 the smallest normalized floating point number different from zero (and >0) that can be represented in a double precision floating point value.