naginterfaces.library.specfun.log_​shifted

naginterfaces.library.specfun.log_shifted(x)[source]

log_shifted returns a value of the shifted logarithmic function, .

For full information please refer to the NAG Library document for s01ba

https://www.nag.com/numeric/nl/nagdoc_28.5/flhtml/s/s01baf.html

Parameters
xfloat

The argument of the function.

Returns
lnx1float

The value of the shifted logarithmic function, .

Raises
NagValueError
(errno )

On entry, .

Constraint: .

Notes

log_shifted computes values of , retaining full relative precision even when is small. The function is based on the Chebyshev expansion

Setting , and choosing , the expansion is valid in the domain .

Outside this domain, is computed by the standard logarithmic function.

References

Lyusternik, L A, Chervonenkis, O A and Yanpolskii, A R, 1965, Handbook for Computing Elementary Functions, p. 57, Pergamon Press