AdvancedMath.IntegralEi Method
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AdvancedMathIntegralEi Method

Computes the principal value of the exponential integral.

Namespace:  Meta.Numerics.Functions
Assembly:  Meta.Numerics (in Meta.Numerics.dll) Version: 4.0.5.0 (4.0.5.0)
Syntax
public static double IntegralEi(
	double x
)

Parameters

x
Type: SystemDouble
The argument, which must be non-negative.

Return Value

Type: Double
The value of Ei(x).
Exceptions
ExceptionCondition
ArgumentOutOfRangeExceptionx is negative.
Remarks

The function Ei(x) appears in the evaluation of some indefinite integrals involving exponents and in number theory in the approximation li(x) = Ei(ln x) to the cumulative distribution of primes.

Ei(x) is related to the real part of E1(x) for negative arguments by:

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

See Also