Fermi_integral
- plasmapy.formulary.mathematics.Fermi_integral(x: complex | ndarray, j: complex | ndarray) complex | ndarray [source]
Calculate the complete Fermi-Dirac integral.
- Parameters:
- Returns:
integral – Complete Fermi-Dirac integral for given argument and order.
- Return type:
- Raises:
TypeError – If the argument is invalid.
UnitsError – If the argument is a
Quantity
but is not dimensionless.ValueError – If the argument is not entirely finite.
Notes
The complete Fermi-Dirac integral is defined as:
\[F_j (x) = \frac{1}{Γ(j+1)} \int_0^∞ \frac{t^j}{\exp{(t-x)} + 1} dt\]for \(j > 0\).
This is equivalent to the following polylogarithm function:
\[F_j (x) = -Li_{j+1}\left(-e^{x}\right)\]Warning
At present this function is limited to relatively small arguments due to limitations in
mpmath.polylog
.Examples
>>> Fermi_integral(0, 0) (0.6931471805599453-0j) >>> Fermi_integral(1, 0) (1.3132616875182228-0j) >>> Fermi_integral(1, 1) (1.8062860704447743-0j)