- publishing free software manuals
 GNU Scientific Library Reference Manual - Third Edition (v1.12) by M. Galassi, J. Davies, J. Theiler, B. Gough, G. Jungman, P. Alken, M. Booth, F. RossiPaperback (6"x9"), 592 pages, 60 figuresISBN 0954612078RRP £24.95 (\$39.95)

## 7.25 Logarithm and Related Functions

Information on the properties of the Logarithm function can be found in Abramowitz & Stegun, Chapter 4. The functions described in this section are declared in the header file ‘gsl_sf_log.h’.

Function: double gsl_sf_log (double x)
Function: int gsl_sf_log_e (double x, gsl_sf_result * result)
These routines compute the logarithm of x, \log(x), for x > 0.
Function: double gsl_sf_log_abs (double x)
Function: int gsl_sf_log_abs_e (double x, gsl_sf_result * result)
These routines compute the logarithm of the magnitude of x, \log(|x|), for x \ne 0.
Function: int gsl_sf_complex_log_e (double zr, double zi, gsl_sf_result * lnr, gsl_sf_result * theta)
This routine computes the complex logarithm of z = z_r + i z_i. The results are returned as lnr, theta such that \exp(lnr + i \theta) = z_r + i z_i, where \theta lies in the range [-\pi,\pi].
Function: double gsl_sf_log_1plusx (double x)
Function: int gsl_sf_log_1plusx_e (double x, gsl_sf_result * result)
These routines compute \log(1 + x) for x > -1 using an algorithm that is accurate for small x.
Function: double gsl_sf_log_1plusx_mx (double x)
Function: int gsl_sf_log_1plusx_mx_e (double x, gsl_sf_result * result)
These routines compute \log(1 + x) - x for x > -1 using an algorithm that is accurate for small x.
 ISBN 0954612078 GNU Scientific Library Reference Manual - Third Edition (v1.12) See the print edition