Math2.org Math Tables: Special Functions

(Math)

Some of these functions I have seen defined under both intervals (0 to x) and (x to inf). In that case, both variant definitions are listed.
gamma = Euler's constant = 0.5772156649...

[Gamma](x) = [integral](0 to inf)tx-1 e-t dt (Gamma function)

B(x,y) = [integral](0 to 1)tx-1 (1-t)y-1dt (Beta function)

Ei(x) = [integral](x to inf)e-t/t dt (exponential integral) or it's variant, NONEQUIVALENT form:

Ei(x) = + ln(x) + [integral](0 to x)(e^t - 1)/t dt = gamma + ln(x) + (sum)(n=1..inf)x^n/(n*n!)
li(x) = [integral](2 to x)1/ln(t) dt (logarithmic integral)
Si(x) = [integral](x to inf)sin(t)/t dt (sine integral) or it's variant, NONEQUIVALENT form:
Si(x) = [integral](0 to x)sin(t)/t dt = PI/2 - [integral](x to inf)sin(t)/t dt

Ci(x) = [integral](x to inf)cos(t)/t dt (cosine integral) or it's variant, NONEQUIVALENT form:
Ci(x) = - [integral](x to inf)cos(t)/t dt = gamma + ln(x) + [integral](0 to x) (cos(t) - 1) / t dt (cosine integral)

Chi(x) = gamma + ln(x) + [integral](0 to x)(cosh(t)-1)/t dt (hyperbolic cosine integral)
Shi(x) = [integral](0 to x)sinh(t)/t dt (hyperbolic sine integral)

\[ Erf(x) = 2 \pi<sup>{2}</sup> \int_0^x exp(-t^2) \, dt \] \[ = 2 \pi<sup>{2}</sup> \sum_0^\infty (-1)^n x<sup>2n+1</sup> n!<sup>-1</sup> (2n+1)<sup>-1</sup> \] (error function)

\[ FresnelC(x) = \int_0^x \cos(\frac{1}{2}\pi t^2) \, dt \]

\[ FresnelS(x) = \int_0^x \sin(\frac{1}{2}\pi t^2) \, dt \]

dilog(x) = [integral](1 to x)ln(t) (1-t)-1 dt

\[ Psi(x) = \frac{d}{dx} ln(\Gamma(x)) \]

Psi(n,x) = nth derivative of Psi(x)

W(x) = inverse of x ex

\[ L_n(x) = \frac{1}{n!} e^x (x^n e<sup>-x</sup>)<sup>(n)</sup> \] (laguerre polynomial degree n. (n) meaning nth derivative)

\[ Zeta(s) = \sum<sub>n=1</sub><sup>\infty</sup> n<sup>-s</sup> \]

Dirichlet's beta function \[ B(x) = \sum<sub>n=0</sub>^\infty (-1)^n (2n+1)<sup>-x</sup> \]


Theorems with hyperlinks have proofs, related theorems, discussions, and/or other info.