Logarithmic integral function: Difference between revisions

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offset logarithmic integral
The claims that li is mainly used in number theory and that Li gives a better estimate are incorrect and were removed
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(see [[big O notation]]).
 
The logarithmic integral isfinds mainlyapplication importantin becausemany areas, in particular it occursis used is in estimates of [[prime number]] densities, especiallysuch inas the [[prime number theorem]]:
 
:π(''x'') ~ li(''x'') ~ Li(''x'')
 
where π(''x'') denotes the number of primes smaller than or equal to ''x'', and Li(''x'') is the [[offset logarithmic integral]] function, related to li(''x'') by Li(''x'') = li(''x'') - li(2).
 
The offset logarithmic integral gives a slightly better estimate to the π function than li(''x''). The function li(''x'') is related to the ''[[exponential integral]]'' Ei(''x'') via the equation
 
:li(''x'') = Ei (ln (''x''))    for all positive real ''x'' ≠ 1.