Blame doc/specfunc-lambert.rst
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.. index::
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single: W function
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single: Lambert function
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Lambert's W functions, :math:`W(x)`, are defined to be solutions
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of the equation :math:`W(x) \exp(W(x)) = x`. This function has
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multiple branches for :math:`x < 0`; however, it has only
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two real-valued branches. We define :math:`W_0(x)` to be the
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principal branch, where :math:`W > -1` for :math:`x < 0`, and
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:math:`W_{-1}(x)`
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to be the other real branch, where
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:math:`W < -1` for :math:`x < 0`. The Lambert functions are
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declared in the header file :file:`gsl_sf_lambert.h`.
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.. function:: double gsl_sf_lambert_W0 (double x)
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int gsl_sf_lambert_W0_e (double x, gsl_sf_result * result)
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These compute the principal branch of the Lambert W function, :math:`W_0(x)`.
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.. exceptions: GSL_EDOM, GSL_EMAXITER
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.. function:: double gsl_sf_lambert_Wm1 (double x)
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int gsl_sf_lambert_Wm1_e (double x, gsl_sf_result * result)
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These compute the secondary real-valued branch of the Lambert W function,
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:math:`W_{-1}(x)`.
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.. exceptions: GSL_EDOM, GSL_EMAXITER
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