AdvancedMathIntegralE Method

public static double IntegralE(
	int n,
	double x
)

Public Shared Function IntegralE ( 
	n As Integer,
	x As Double
) As Double

public:
static double IntegralE(
	int n, 
	double x
)

static member IntegralE : 
        n : int * 
        x : float -> float 

Parameters

n  Int32

The order parameter.

x  Double

The argument, which must be non-negative.

Return Value

The generalized exponential integral is defined as:

It is related to the incomplete Gamma function (Gamma(Double, Double)) for negative, integer shape parameters.

For n=1, it expressible as a simple power series.

For negative x, E₁(x) develops an imaginary part, but its real part is given by the Ei(x) function (IntegralEi(Double)).

To compute E₁(z) in the entire complex plane, use Ein(Complex).

Sometimes the function E₁(z) is called the exponential integral, and sometimes that name is used for Ei(x). In hydrology, E₁(x) is sometimes called the Well function.

Reference

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