Chebyshev approximations for the exponential integral

Authors:
W. J. Cody and Henry C. Thacher

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

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Abstract: The computation of the exponential integral , , using rational Chebyshev approximations is discussed. The necessary approximations are presented in well-conditioned forms for the intervals , , and . Maximal relative errors are as low as from . In addition, the value of the zero of is presented to 30 decimal places.

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DOI:
https://doi.org/10.1090/S0025-5718-1969-0242349-2

Article copyright:
© Copyright 1969
American Mathematical Society