Chebyshev approximations for the exponential integral $\textrm {Ei}(x)$
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- by W. J. Cody and Henry C. Thacher PDF
- Math. Comp. 23 (1969), 289-303 Request permission
Abstract:
The computation of the exponential integral $Ei(x)$, $x > 0$, using rational Chebyshev approximations is discussed. The necessary approximations are presented in well-conditioned forms for the intervals $(0,6]$, $[6,12]$, $[12,24]$ and $[24,\infty )$. Maximal relative errors are as low as from $8 \times {10^{ - 19}}to2 \times {10^{ - 21}}$. In addition, the value of the zero of $Ei(x)$ is presented to 30 decimal places.References
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Additional Information
- © Copyright 1969 American Mathematical Society
- Journal: Math. Comp. 23 (1969), 289-303
- MSC: Primary 65.25
- DOI: https://doi.org/10.1090/S0025-5718-1969-0242349-2
- MathSciNet review: 0242349