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=head1 NAME

w_of_z, im_w_of_x - Faddeeva's rescaled complex error function

=head1 SYNOPSIS

B<#include <cerf.h>>

B<double _Complex w_of_z ( double _Complex z );>

B<double im_w_of_x ( double x );>

=head1 DESCRIPTION

Faddeeva's rescaled complex error function w(z), also called the plasma dispersion function.

B<w_of_z> returns w(z) = exp(-z^2) * erfc(-i*z).

B<im_w_of_x> returns Im[w(x)].

=head1 REFERENCES

To compute w(z), a combination of two algorithms is used:

For sufficiently large |z|, a continued-fraction expansion similar
to those described by Gautschi (1970) and Poppe & Wijers (1990).

Otherwise, Algorithm 916 by Zaghloul & Ali (2011), which is
generally competitive at small |z|,
and more accurate than the Poppe & Wijers expansion in some regions,
e.g. in the vicinity of z=1+i.

To compute Im[w(x)], Chebyshev polynomials and continous fractions are used.

Milton Abramowitz and Irene M. Stegun, "Handbook of Mathematical Functions", National Bureau of Standards (1964): Formula (7.1.3) introduces the nameless function w(z). 

Walter Gautschi, "Efficient computation of the complex error function," SIAM J. Numer. Anal. 7, 187 (1970).

G. P. M. Poppe and C. M. J. Wijers, "More efficient computation of the complex error function," ACM Trans. Math. Soft. 16, 38 (1990).

Mofreh R. Zaghloul and Ahmed N. Ali, "Algorithm 916: Computing the Faddeyeva and Voigt Functions," ACM Trans. Math. Soft. 38, 15 (2011).

Steven G. Johnson, http://ab-initio.mit.edu/Faddeeva

=head1 SEE ALSO

This function is used to compute several other complex error functions:
B<dawson(3)>, B<voigt(3)>, B<cerf(3)>, B<erfcx(3)>, B<erfi(3)>.

Homepage: http://apps.jcns.fz-juelich.de/libcerf

=head1 AUTHORS

Steven G. Johnson, http://math.mit.edu/~stevenj,
  Massachusetts Institute of Technology,
  researched the numerics, and implemented the Faddeeva function.

Joachim Wuttke <j.wuttke@fz-juelich.de>, Forschungszentrum Juelich,
  reorganized the code into a library, and wrote this man page.

Please report bugs to the authors.

=head1 COPYING

Copyright (c) 2012 Massachusetts Institute of Technology

Copyright (c) 2013 Forschungszentrum Juelich GmbH

Software: MIT License.

This documentation: Creative Commons Attribution Share Alike.
