1 @cindex Fermi-Dirac function
3 The functions described in this section are declared in the header file
4 @file{gsl_sf_fermi_dirac.h}.
7 * Complete Fermi-Dirac Integrals::
8 * Incomplete Fermi-Dirac Integrals::
11 @node Complete Fermi-Dirac Integrals
12 @subsection Complete Fermi-Dirac Integrals
13 @cindex complete Fermi-Dirac integrals
14 @cindex Fj(x), Fermi-Dirac integral
15 The complete Fermi-Dirac integral @math{F_j(x)} is given by,
19 F_j(x) := {1\over\Gamma(j+1)} \int_0^\infty dt {t^j \over (\exp(t-x) + 1)}
26 F_j(x) := (1/\Gamma(j+1)) \int_0^\infty dt (t^j / (\exp(t-x) + 1))
30 Note that the Fermi-Dirac integral is sometimes defined without the
31 normalisation factor in other texts.
33 @deftypefun double gsl_sf_fermi_dirac_m1 (double @var{x})
34 @deftypefunx int gsl_sf_fermi_dirac_m1_e (double @var{x}, gsl_sf_result * @var{result})
35 These routines compute the complete Fermi-Dirac integral with an index of @math{-1}.
36 This integral is given by
37 @c{$F_{-1}(x) = e^x / (1 + e^x)$}
38 @math{F_@{-1@}(x) = e^x / (1 + e^x)}.
39 @comment Exceptional Return Values: GSL_EUNDRFLW
42 @deftypefun double gsl_sf_fermi_dirac_0 (double @var{x})
43 @deftypefunx int gsl_sf_fermi_dirac_0_e (double @var{x}, gsl_sf_result * @var{result})
44 These routines compute the complete Fermi-Dirac integral with an index of @math{0}.
45 This integral is given by @math{F_0(x) = \ln(1 + e^x)}.
46 @comment Exceptional Return Values: GSL_EUNDRFLW
49 @deftypefun double gsl_sf_fermi_dirac_1 (double @var{x})
50 @deftypefunx int gsl_sf_fermi_dirac_1_e (double @var{x}, gsl_sf_result * @var{result})
51 These routines compute the complete Fermi-Dirac integral with an index of @math{1},
52 @math{F_1(x) = \int_0^\infty dt (t /(\exp(t-x)+1))}.
53 @comment Exceptional Return Values: GSL_EUNDRFLW, GSL_EOVRFLW
56 @deftypefun double gsl_sf_fermi_dirac_2 (double @var{x})
57 @deftypefunx int gsl_sf_fermi_dirac_2_e (double @var{x}, gsl_sf_result * @var{result})
58 These routines compute the complete Fermi-Dirac integral with an index
60 @math{F_2(x) = (1/2) \int_0^\infty dt (t^2 /(\exp(t-x)+1))}.
61 @comment Exceptional Return Values: GSL_EUNDRFLW, GSL_EOVRFLW
64 @deftypefun double gsl_sf_fermi_dirac_int (int @var{j}, double @var{x})
65 @deftypefunx int gsl_sf_fermi_dirac_int_e (int @var{j}, double @var{x}, gsl_sf_result * @var{result})
66 These routines compute the complete Fermi-Dirac integral with an integer
68 @math{F_j(x) = (1/\Gamma(j+1)) \int_0^\infty dt (t^j /(\exp(t-x)+1))}.
69 @comment Complete integral F_j(x) for integer j
70 @comment Exceptional Return Values: GSL_EUNDRFLW, GSL_EOVRFLW
73 @deftypefun double gsl_sf_fermi_dirac_mhalf (double @var{x})
74 @deftypefunx int gsl_sf_fermi_dirac_mhalf_e (double @var{x}, gsl_sf_result * @var{result})
75 These routines compute the complete Fermi-Dirac integral
78 @comment Exceptional Return Values: GSL_EUNDRFLW, GSL_EOVRFLW
81 @deftypefun double gsl_sf_fermi_dirac_half (double @var{x})
82 @deftypefunx int gsl_sf_fermi_dirac_half_e (double @var{x}, gsl_sf_result * @var{result})
83 These routines compute the complete Fermi-Dirac integral
86 @comment Exceptional Return Values: GSL_EUNDRFLW, GSL_EOVRFLW
89 @deftypefun double gsl_sf_fermi_dirac_3half (double @var{x})
90 @deftypefunx int gsl_sf_fermi_dirac_3half_e (double @var{x}, gsl_sf_result * @var{result})
91 These routines compute the complete Fermi-Dirac integral
94 @comment Exceptional Return Values: GSL_EUNDRFLW, GSL_EOVRFLW
98 @node Incomplete Fermi-Dirac Integrals
99 @subsection Incomplete Fermi-Dirac Integrals
100 @cindex incomplete Fermi-Dirac integral
101 @cindex Fj(x,b), incomplete Fermi-Dirac integral
102 The incomplete Fermi-Dirac integral @math{F_j(x,b)} is given by,
106 F_j(x,b) := {1\over\Gamma(j+1)} \int_b^\infty dt {t^j \over (\exp(t-x) + 1)}
113 F_j(x,b) := (1/\Gamma(j+1)) \int_b^\infty dt (t^j / (\Exp(t-x) + 1))
117 @deftypefun double gsl_sf_fermi_dirac_inc_0 (double @var{x}, double @var{b})
118 @deftypefunx int gsl_sf_fermi_dirac_inc_0_e (double @var{x}, double @var{b}, gsl_sf_result * @var{result})
119 These routines compute the incomplete Fermi-Dirac integral with an index
121 @c{$F_0(x,b) = \ln(1 + e^{b-x}) - (b-x)$}
122 @math{F_0(x,b) = \ln(1 + e^@{b-x@}) - (b-x)}.
123 @comment Exceptional Return Values: GSL_EUNDRFLW, GSL_EDOM