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alglib
 Post subject: exponentialintegralei(x)
PostPosted: Fri Apr 15, 2011 2:14 pm 
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Posts: 3
How great x can be?
I try Ei(100)=2.7e41. It is wrong. How ti calculate such great numbers7
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Doug Jenkins
 Post subject: Re: exponentialintegralei(x)
PostPosted: Sat Apr 16, 2011 12:08 am 
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Posts: 63
Why do you think it is wrong?

Wolfram Alpha gives the same result.

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alglib
 Post subject: Re: exponentialintegralei(x)
PostPosted: Sat Apr 16, 2011 2:43 am 
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Posts: 3
Sorry. Misunderstood.
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alglib
 Post subject: Re: exponentialintegralei(x)
PostPosted: Sat Apr 16, 2011 10:37 am 
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How can I calculate big values of thid functions?
x Ei(x,1)
1.670000e+002 1.768184e-075
1.680000e+002 6.466293e-076
1.690000e+002 2.364822e-076
1.700000e+002 8.648816e-077
1.710000e+002 -1.000000e+000
1.720000e+002 -1.000000e+000
1.730000e+002 -1.000000e+000
1.740000e+002 -1.000000e+000
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Doug Jenkins
 Post subject: Re: exponentialintegralei(x)
PostPosted: Sun Apr 17, 2011 11:04 pm 
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Posts: 63
alglib wrote:
How can I calculate big values of thid functions?
x Ei(x,1)
1.670000e+002 1.768184e-075
1.680000e+002 6.466293e-076
1.690000e+002 2.364822e-076
1.700000e+002 8.648816e-077
1.710000e+002 -1.000000e+000
1.720000e+002 -1.000000e+000
1.730000e+002 -1.000000e+000
1.740000e+002 -1.000000e+000


170 seems to be the Alglib limit for this function. The equivalent function in the Xnumbers package goes up to 701.

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