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CD ROM Paradise Collection 4
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CD ROM Paradise Collection 4 1995 Nov.iso
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LIBRARY
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LI.LI
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1993-11-14
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742b
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28 lines
# library li.(x)
# li(x) is the log integral function,
# li(x) = inte(1/ln(t), t,0,x) = ei(ln(x)), li'(x)=1/ln(x).
# li(n,x) is the incomplete log integral function, li(n,x)=ei(n,ln(x)),
# li(n,x)=inte(ln(t)^n, t,0,x), d(li(n,x),x)=ln(x)^n, li(-1, x)=li(x),
# li(0,x)=x.
# See also: gamma, ei, li.
# d(li(n_,x_),x_):= ln(x)^n
# d(li(x_) ,x_) := 1/ln(x)
# li(n_,x_) := if(n>=1, -n*li(n-1,x)+ln(x)^n*x,
if(n<-1, (-li(n+1,x)+ln(x)^(n+1)*x)/(n+1)))
li(0) := 0
li(1):=1
#li(2):=1
#li(n_):=if(n>2, if(isinteger(n), (n-1)!, (n-1)*li(n-1)))
#li(n_):=if(n>0 and numerical==on, sqrt(2*pi)*n^(n-0.5)*exp(-n)*(1+1/(12*n)))
#li(0,0) := 0
li(n_,0) := 0
#li(n_,inf) := inf
#li(n_,-inf) := 0
li(-1,x_) := li(x)
li(0,x_) := x