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Diffstat (limited to 'gsl-1.9/doc/specfunc-lambert.texi')
| -rw-r--r-- | gsl-1.9/doc/specfunc-lambert.texi | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/gsl-1.9/doc/specfunc-lambert.texi b/gsl-1.9/doc/specfunc-lambert.texi new file mode 100644 index 0000000..c05d23d --- /dev/null +++ b/gsl-1.9/doc/specfunc-lambert.texi @@ -0,0 +1,28 @@ +@cindex W function +@cindex Lambert function + +Lambert's W functions, @math{W(x)}, are defined to be solutions +of the equation @math{W(x) \exp(W(x)) = x}. This function has +multiple branches for @math{x < 0}; however, it has only +two real-valued branches. We define @math{W_0(x)} to be the +principal branch, where @math{W > -1} for @math{x < 0}, and +@c{$W_{-1}(x)$} +@math{W_@{-1@}(x)} to be the other real branch, where +@math{W < -1} for @math{x < 0}. The Lambert functions are +declared in the header file @file{gsl_sf_lambert.h}. + + +@deftypefun double gsl_sf_lambert_W0 (double @var{x}) +@deftypefunx int gsl_sf_lambert_W0_e (double @var{x}, gsl_sf_result * @var{result}) +These compute the principal branch of the Lambert W function, @math{W_0(x)}. +@comment exceptions: GSL_EDOM, GSL_EMAXITER +@end deftypefun + +@deftypefun double gsl_sf_lambert_Wm1 (double @var{x}) +@deftypefunx int gsl_sf_lambert_Wm1_e (double @var{x}, gsl_sf_result * @var{result}) +These compute the secondary real-valued branch of the Lambert W function, +@c{$W_{-1}(x)$} +@math{W_@{-1@}(x)}. +@comment exceptions: GSL_EDOM, GSL_EMAXITER +@end deftypefun + |