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7 Error Functions, Dawson’s and Fresnel IntegralsProperties

§7.2 Definitions

Contents
  1. §7.2(i) Error Functions
  2. §7.2(ii) Dawson’s Integral
  3. §7.2(iii) Fresnel Integrals
  4. §7.2(iv) Auxiliary Functions
  5. §7.2(v) Goodwin–Staton Integral

§7.2(i) Error Functions

7.2.1 \operatorname{erf}z=\frac{2}{\sqrt{\pi}}\int_{0}^{z}e^{-t^{2}}\,\mathrm{d}t,
7.2.2 \operatorname{erfc}z=\frac{2}{\sqrt{\pi}}\int_{z}^{\infty}e^{-t^{2}}\,\mathrm{%
d}t=1-\operatorname{erf}z,
7.2.3 w\left(z\right)=e^{-z^{2}}\left(1+\frac{2i}{\sqrt{\pi}}\int_{0}^{z}e^{t^{2}}\,%
\mathrm{d}t\right)=e^{-z^{2}}\operatorname{erfc}\left(-iz\right).

\operatorname{erf}z, \operatorname{erfc}z, and w\left(z\right) are entire functions of z, as is F\left(z\right) in the next subsection.

Values at Infinity

7.2.4
\lim_{z\to\infty}\operatorname{erf}z=1,
\lim_{z\to\infty}\operatorname{erfc}z=0, |\operatorname{ph}z|\leq\tfrac{1}{4}\pi-\delta(<\tfrac{1}{4}\pi).

§7.2(ii) Dawson’s Integral

7.2.5 F\left(z\right)=e^{-z^{2}}\int_{0}^{z}e^{t^{2}}\,\mathrm{d}t.

§7.2(iii) Fresnel Integrals

7.2.7 C\left(z\right)=\int_{0}^{z}\cos\left(\tfrac{1}{2}\pi t^{2}\right)\,\mathrm{d}t,
7.2.8 S\left(z\right)=\int_{0}^{z}\sin\left(\tfrac{1}{2}\pi t^{2}\right)\,\mathrm{d}t,

\mathcal{F}\left(z\right), C\left(z\right), and S\left(z\right) are entire functions of z, as are \mathrm{f}\left(z\right) and \mathrm{g}\left(z\right) in the next subsection.

Values at Infinity

7.2.9
\lim_{x\to\infty}C\left(x\right)=\tfrac{1}{2},
\lim_{x\to\infty}S\left(x\right)=\tfrac{1}{2}.

§7.2(iv) Auxiliary Functions

7.2.10 \mathrm{f}\left(z\right)=\left(\tfrac{1}{2}-S\left(z\right)\right)\cos\left(%
\tfrac{1}{2}\pi z^{2}\right)-\left(\tfrac{1}{2}-C\left(z\right)\right)\sin%
\left(\tfrac{1}{2}\pi z^{2}\right),
7.2.11 \mathrm{g}\left(z\right)=\left(\tfrac{1}{2}-C\left(z\right)\right)\cos\left(%
\tfrac{1}{2}\pi z^{2}\right)+\left(\tfrac{1}{2}-S\left(z\right)\right)\sin%
\left(\tfrac{1}{2}\pi z^{2}\right).

§7.2(v) Goodwin–Staton Integral

7.2.12 G\left(z\right)=\int_{0}^{\infty}\frac{e^{-t^{2}}}{t+z}\,\mathrm{d}t,|\operatorname{ph}z|<\pi.