7.4 Symmetry7.6 Series Expansions

§7.5 Interrelations

7.5.1\mathop{F\/}\nolimits\!\left(z\right)=\tfrac{1}{2}i\sqrt{\pi}\left(e^{{-z^{2}}}-\mathop{w\/}\nolimits\!\left(z\right)\right)=-\tfrac{1}{2}i\sqrt{\pi}e^{{-z^{2}}}\mathop{\mathrm{erf}\/}\nolimits\!\left(iz\right).
7.5.2\mathop{C\/}\nolimits\!\left(z\right)+i\mathop{S\/}\nolimits\!\left(z\right)=\tfrac{1}{2}(1+i)-\mathop{\mathcal{F}\/}\nolimits\!\left(z\right).
7.5.3\mathop{C\/}\nolimits\!\left(z\right)=\tfrac{1}{2}+\mathop{\mathrm{f}\/}\nolimits\!\left(z\right)\mathop{\sin\/}\nolimits\!\left(\tfrac{1}{2}\pi z^{2}\right)-\mathop{\mathrm{g}\/}\nolimits\!\left(z\right)\mathop{\cos\/}\nolimits\!\left(\tfrac{1}{2}\pi z^{2}\right),
7.5.4\mathop{S\/}\nolimits\!\left(z\right)=\tfrac{1}{2}-\mathop{\mathrm{f}\/}\nolimits\!\left(z\right)\mathop{\cos\/}\nolimits\!\left(\tfrac{1}{2}\pi z^{2}\right)-\mathop{\mathrm{g}\/}\nolimits\!\left(z\right)\mathop{\sin\/}\nolimits\!\left(\tfrac{1}{2}\pi z^{2}\right).
7.5.5e^{{-\frac{1}{2}\pi iz^{2}}}\mathop{\mathcal{F}\/}\nolimits\!\left(z\right)=\mathop{\mathrm{g}\/}\nolimits\!\left(z\right)+i\mathop{\mathrm{f}\/}\nolimits\!\left(z\right).
7.5.6e^{{\pm\frac{1}{2}\pi iz^{2}}}(\mathop{\mathrm{g}\/}\nolimits\!\left(z\right)\pm i\mathop{\mathrm{f}\/}\nolimits\!\left(z\right))=\tfrac{1}{2}(1\pm i)-(\mathop{C\/}\nolimits\!\left(z\right)\pm i\mathop{S\/}\nolimits\!\left(z\right)).

In (7.5.8)–(7.5.10)

7.5.7\zeta=\tfrac{1}{2}\sqrt{\pi}(1\mp i)z,

and either all upper signs or all lower signs are taken throughout.

7.5.8\mathop{C\/}\nolimits\!\left(z\right)\pm i\mathop{S\/}\nolimits\!\left(z\right)=\tfrac{1}{2}(1\pm i)\mathop{\mathrm{erf}\/}\nolimits\zeta.
7.5.9\mathop{C\/}\nolimits\!\left(z\right)\pm i\mathop{S\/}\nolimits\!\left(z\right)=\tfrac{1}{2}(1\pm i)\left(1-e^{{\pm\frac{1}{2}\pi iz^{2}}}\mathop{w\/}\nolimits\!\left(i\zeta\right)\right).
7.5.10\mathop{\mathrm{g}\/}\nolimits\!\left(z\right)\pm i\mathop{\mathrm{f}\/}\nolimits\!\left(z\right)=\tfrac{1}{2}(1\pm i)e^{{\zeta^{2}}}\mathop{\mathrm{erfc}\/}\nolimits\zeta.
7.5.11|\mathop{\mathcal{F}\/}\nolimits\!\left(x\right)|^{2}={\mathop{\mathrm{f}\/}\nolimits^{{2}}}\!\left(x\right)+{\mathop{\mathrm{g}\/}\nolimits^{{2}}}\!\left(x\right),x\geq 0,
7.5.12|\mathop{\mathcal{F}\/}\nolimits\!\left(x\right)|^{2}=2+{\mathop{\mathrm{f}\/}\nolimits^{{2}}}\!\left(-x\right)+{\mathop{\mathrm{g}\/}\nolimits^{{2}}}\!\left(-x\right)-2\sqrt{2}\mathop{\cos\/}\nolimits\!\left(\tfrac{1}{4}\pi+\tfrac{1}{2}\pi x^{2}\right)\mathop{\mathrm{f}\/}\nolimits\!\left(-x\right)-2\sqrt{2}\mathop{\cos\/}\nolimits\!\left(\tfrac{1}{4}\pi-\tfrac{1}{2}\pi x^{2}\right)\mathop{\mathrm{g}\/}\nolimits\!\left(-x\right),x\leq 0.

See Figure 7.3.4.

7.5.13\mathop{G\/}\nolimits\!\left(x\right)=\sqrt{\pi}\mathop{F\/}\nolimits\!\left(x\right)-\tfrac{1}{2}e^{{-x^{2}}}\mathop{\mathrm{Ei}\/}\nolimits\!\left(x^{2}\right),x>0.

For \mathop{\mathrm{Ei}\/}\nolimits\!\left(x\right) see §6.2(i).