Difference between revisions of "Relationship between Sievert integral and exponential integral E"
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==Theorem== | ==Theorem== | ||
The following formula holds for $x \geq 0$ and $0 < \theta < \dfrac{\pi}{2}$: | The following formula holds for $x \geq 0$ and $0 < \theta < \dfrac{\pi}{2}$: | ||
− | $$S(x,\theta)=\ | + | $$S(x,\theta)=S\left(x,\dfrac{\pi}{2} \right) - \displaystyle\sum_{k=0}^{\infty} \alpha_k (\cos(\theta))^{2k+1} E_{2k+2} \left( \dfrac{x}{\cos(\theta)} \right),$$ |
− | where $S$ denotes the [[Sievert integral | + | where $S$ denotes the [[Sievert integral]], $\alpha_k$ is defined by $\alpha_0 := 1$ and for $k=1,2,3,\ldots$, $\alpha_k := \dfrac{1 \cdot 3 \cdot 5 \cdot \ldots \cdot (2k+1)}{2 \cdot 4 \cdot 6 \cdot \ldots \cdot 2k}$, $\cos$ denotes [[cosine]], and $E_{2k+2}$ denotes the [[exponential integral E]]. |
==Proof== | ==Proof== | ||
==References== | ==References== | ||
− | {{BookReference|Handbook of mathematical functions|1964|Milton Abramowitz|author2=Irene A. Stegun|prev= | + | {{BookReference|Handbook of mathematical functions|1964|Milton Abramowitz|author2=Irene A. Stegun|prev=Asymptotic behavior of Sievert integral|next=Relationship between Sievert integral and Bessel K}}: $27.4.2$ |
[[Category:Theorem]] | [[Category:Theorem]] | ||
[[Category:Unproven]] | [[Category:Unproven]] |
Latest revision as of 02:11, 21 December 2016
Theorem
The following formula holds for $x \geq 0$ and $0 < \theta < \dfrac{\pi}{2}$: $$S(x,\theta)=S\left(x,\dfrac{\pi}{2} \right) - \displaystyle\sum_{k=0}^{\infty} \alpha_k (\cos(\theta))^{2k+1} E_{2k+2} \left( \dfrac{x}{\cos(\theta)} \right),$$ where $S$ denotes the Sievert integral, $\alpha_k$ is defined by $\alpha_0 := 1$ and for $k=1,2,3,\ldots$, $\alpha_k := \dfrac{1 \cdot 3 \cdot 5 \cdot \ldots \cdot (2k+1)}{2 \cdot 4 \cdot 6 \cdot \ldots \cdot 2k}$, $\cos$ denotes cosine, and $E_{2k+2}$ denotes the exponential integral E.
Proof
References
1964: Milton Abramowitz and Irene A. Stegun: Handbook of mathematical functions ... (previous) ... (next): $27.4.2$