LaTeX to CAS translator

This mockup demonstrates the concept of TeX to Computer Algebra System (CAS) conversion.

The demo-application converts LaTeX functions which directly translate to CAS counterparts.

Functions without explicit CAS support are available for translation via a DRMF package (under development).

The following LaTeX input ...

{\displaystyle \Phi(z,s,a)=\frac{1}{2a^s}+ \frac{1}{z^a}\sum_{k=1}^\infty \frac{e^{-2\pi i(k-1)a}\Gamma(1-s,a(-2\pi i(k-1)-\log(z)))} {(-2\pi i(k-1)-\log(z))^{1-s}}+ \frac{e^{2\pi ika}\Gamma(1-s,a(2\pi ik-\log(z)))}{(2\pi ik-\log(z))^{1-s}} }

${\displaystyle \Phi (z,s,a)={\frac {1}{2a^{s}}}+{\frac {1}{z^{a}}}\sum _{k=1}^{\infty }{\frac {e^{-2\pi i(k-1)a}\Gamma (1-s,a(-2\pi i(k-1)-\log(z)))}{(-2\pi i(k-1)-\log(z))^{1-s}}}+{\frac {e^{2\pi ika}\Gamma (1-s,a(2\pi ik-\log(z)))}{(2\pi ik-\log(z))^{1-s}}}}$

... is translated to the CAS output ...

Semantic latex: \Phi(z , s , a) = \frac{1}{2a^s} + \frac{1}{z^a} \sum_{k=1}^\infty \frac{\expe^{- 2 \cpi \iunit(k - 1) a} \incGamma@{1 - s}{a(- 2 \cpi \iunit(k - 1) - \log(z))}}{(- 2 \cpi \iunit(k - 1) - \log(z))^{1-s}} + \frac{\expe^{2 \cpi \iunit ka} \incGamma@{1 - s}{a(2 \cpi \iunit k - \log(z))}}{(2 \cpi \iunit k - \log(z))^{1-s}}

Confidence: 0.65182996701405

Mathematica

Translation: \[CapitalPhi][z , s , a] == Divide[1,2*(a)^(s)]+Divide[1,(z)^(a)]*Sum[Divide[Exp[- 2*Pi*I*(k - 1)*a]*Gamma[1 - s, a*(- 2*Pi*I*(k - 1)- Log[z])],(- 2*Pi*I*(k - 1)- Log[z])^(1 - s)]+Divide[Exp[2*Pi*I*k*a]*Gamma[1 - s, a*(2*Pi*I*k - Log[z])],(2*Pi*I*k - Log[z])^(1 - s)], {k, 1, Infinity}, GenerateConditions->None]

Information

Sub Equations

\[CapitalPhi][z , s , a] = Divide[1,2*(a)^(s)]+Divide[1,(z)^(a)]*Sum[Divide[Exp[- 2*Pi*I*(k - 1)*a]*Gamma[1 - s, a*(- 2*Pi*I*(k - 1)- Log[z])],(- 2*Pi*I*(k - 1)- Log[z])^(1 - s)]+Divide[Exp[2*Pi*I*k*a]*Gamma[1 - s, a*(2*Pi*I*k - Log[z])],(2*Pi*I*k - Log[z])^(1 - s)], {k, 1, Infinity}, GenerateConditions->None]

Free variables

\[CapitalPhi]

a

s

z

Symbol info

Pi was translated to: Pi

Logarithm; Example: \log@@{z}

Will be translated to: Log[$0] Constraints: z != 0 Branch Cuts: (-\infty, 0] Relevant links to definitions: DLMF: http://dlmf.nist.gov/4.2#E2 Mathematica: https://reference.wolfram.com/language/ref/Log.html

Incomplete Gamma function (upper); Example: \incGamma@{a}{z}

Will be translated to: Gamma[$0, $1] Relevant links to definitions: DLMF: http://dlmf.nist.gov/8.2#E2 Mathematica: https://reference.wolfram.com/language/ref/Gamma.html

Recognizes e with power as the exponential function. It was translated as a function.

Imaginary unit was translated to: I

Function without DLMF-Definition. We keep it like it is (but delete prefix \ if necessary).

Tests

Symbolic

Test expression: (\[CapitalPhi]*(z , s , a))-(Divide[1,2*(a)^(s)]+Divide[1,(z)^(a)]*Sum[Divide[Exp[- 2*Pi*I*(k - 1)*a]*Gamma[1 - s, a*(- 2*Pi*I*(k - 1)- Log[z])],(- 2*Pi*I*(k - 1)- Log[z])^(1 - s)]+Divide[Exp[2*Pi*I*k*a]*Gamma[1 - s, a*(2*Pi*I*k - Log[z])],(2*Pi*I*k - Log[z])^(1 - s)], {k, 1, Infinity}, GenerateConditions->None])

ERROR:

{
    "result": "ERROR",
    "testTitle": "Simple",
    "testExpression": null,
    "resultExpression": null,
    "wasAborted": false,
    "conditionallySuccessful": false
}

Numeric

SymPy

Translation:

Information

Symbol info

(LaTeX -> SymPy) No translation possible for given token: Cannot extract information from feature set: \incGamma [\incGamma]

Tests

Symbolic

Numeric

Maple

Translation: Phi(z , s , a) = (1)/(2*(a)^(s))+(1)/((z)^(a))*sum((exp(- 2*Pi*I*(k - 1)*a)*GAMMA(1 - s, a*(- 2*Pi*I*(k - 1)- log(z))))/((- 2*Pi*I*(k - 1)- log(z))^(1 - s))+(exp(2*Pi*I*k*a)*GAMMA(1 - s, a*(2*Pi*I*k - log(z))))/((2*Pi*I*k - log(z))^(1 - s)), k = 1..infinity)

Information

Sub Equations

Phi(z , s , a) = (1)/(2*(a)^(s))+(1)/((z)^(a))*sum((exp(- 2*Pi*I*(k - 1)*a)*GAMMA(1 - s, a*(- 2*Pi*I*(k - 1)- log(z))))/((- 2*Pi*I*(k - 1)- log(z))^(1 - s))+(exp(2*Pi*I*k*a)*GAMMA(1 - s, a*(2*Pi*I*k - log(z))))/((2*Pi*I*k - log(z))^(1 - s)), k = 1..infinity)

Free variables

Phi

a

s

z

Symbol info

Pi was translated to: Pi

Logarithm; Example: \log@@{z}

Will be translated to: log($0) Constraints: z != 0 Branch Cuts: (-\infty, 0] Relevant links to definitions: DLMF: http://dlmf.nist.gov/4.2#E2 Maple: https://www.maplesoft.com/support/help/maple/view.aspx?path=log

Incomplete Gamma function (upper); Example: \incGamma@{a}{z}

Will be translated to: GAMMA($0, $1) Relevant links to definitions: DLMF: http://dlmf.nist.gov/8.2#E2 Maple: https://www.maplesoft.com/support/help/maple/view.aspx?path=GAMMA

Recognizes e with power as the exponential function. It was translated as a function.

Imaginary unit was translated to: I

Function without DLMF-Definition. We keep it like it is (but delete prefix \ if necessary).

Tests

Symbolic

Numeric

Dependency Graph Information

Includes

$a$

$\Phi (z,s,a)$

$\Phi (z,s,a)={\frac {1}{2a^{s}}}+{\frac {1}{z^{a}}}\sum _{k=1}^{\infty }{\frac {e^{-2\pi i(k-1)a}\Gamma (1-s,a(-2\pi i(k-1)-\log(z)))}{(-2\pi i(k-1)-\log(z))^{1-s}}}+{\frac {e^{2\pi ika}\Gamma (1-s,a(2\pi ik-\log(z)))}{(2\pi ik-\log(z))^{1-s}}}$

$z$

$s$

Is part of

$\Phi (z,s,a)={\frac {1}{2a^{s}}}+{\frac {1}{z^{a}}}\sum _{k=1}^{\infty }{\frac {e^{-2\pi i(k-1)a}\Gamma (1-s,a(-2\pi i(k-1)-\log(z)))}{(-2\pi i(k-1)-\log(z))^{1-s}}}+{\frac {e^{2\pi ika}\Gamma (1-s,a(2\pi ik-\log(z)))}{(2\pi ik-\log(z))^{1-s}}}$

Complete translation information:

{
  "id" : "FORMULA_7a79399429aafb33d44663240c1d3e18",
  "formula" : "\\Phi(z,s,a)=\\frac{1}{2a^s}+\n\\frac{1}{z^a}\\sum_{k=1}^\\infty\n\\frac{e^{-2\\pi i(k-1)a}\\Gamma(1-s,a(-2\\pi i(k-1)-\\log(z)))}\n     {(-2\\pi i(k-1)-\\log(z))^{1-s}}+\n\\frac{e^{2\\pi ika}\\Gamma(1-s,a(2\\pi ik-\\log(z)))}{(2\\pi ik-\\log(z))^{1-s}}",
  "semanticFormula" : "\\Phi(z , s , a) = \\frac{1}{2a^s} + \\frac{1}{z^a} \\sum_{k=1}^\\infty \\frac{\\expe^{- 2 \\cpi \\iunit(k - 1) a} \\incGamma@{1 - s}{a(- 2 \\cpi \\iunit(k - 1) - \\log(z))}}{(- 2 \\cpi \\iunit(k - 1) - \\log(z))^{1-s}} + \\frac{\\expe^{2 \\cpi \\iunit ka} \\incGamma@{1 - s}{a(2 \\cpi \\iunit k - \\log(z))}}{(2 \\cpi \\iunit k - \\log(z))^{1-s}}",
  "confidence" : 0.651829967014045,
  "translations" : {
    "Mathematica" : {
      "translation" : "\\[CapitalPhi][z , s , a] == Divide[1,2*(a)^(s)]+Divide[1,(z)^(a)]*Sum[Divide[Exp[- 2*Pi*I*(k - 1)*a]*Gamma[1 - s, a*(- 2*Pi*I*(k - 1)- Log[z])],(- 2*Pi*I*(k - 1)- Log[z])^(1 - s)]+Divide[Exp[2*Pi*I*k*a]*Gamma[1 - s, a*(2*Pi*I*k - Log[z])],(2*Pi*I*k - Log[z])^(1 - s)], {k, 1, Infinity}, GenerateConditions->None]",
      "translationInformation" : {
        "subEquations" : [ "\\[CapitalPhi][z , s , a] = Divide[1,2*(a)^(s)]+Divide[1,(z)^(a)]*Sum[Divide[Exp[- 2*Pi*I*(k - 1)*a]*Gamma[1 - s, a*(- 2*Pi*I*(k - 1)- Log[z])],(- 2*Pi*I*(k - 1)- Log[z])^(1 - s)]+Divide[Exp[2*Pi*I*k*a]*Gamma[1 - s, a*(2*Pi*I*k - Log[z])],(2*Pi*I*k - Log[z])^(1 - s)], {k, 1, Infinity}, GenerateConditions->None]" ],
        "freeVariables" : [ "\\[CapitalPhi]", "a", "s", "z" ],
        "tokenTranslations" : {
          "\\cpi" : "Pi was translated to: Pi",
          "\\log" : "Logarithm; Example: \\log@@{z}\nWill be translated to: Log[$0]\nConstraints: z != 0\nBranch Cuts: (-\\infty, 0]\nRelevant links to definitions:\nDLMF:         http://dlmf.nist.gov/4.2#E2\nMathematica:  https://reference.wolfram.com/language/ref/Log.html",
          "\\incGamma" : "Incomplete Gamma function (upper); Example: \\incGamma@{a}{z}\nWill be translated to: Gamma[$0, $1]\nRelevant links to definitions:\nDLMF:         http://dlmf.nist.gov/8.2#E2\nMathematica:  https://reference.wolfram.com/language/ref/Gamma.html",
          "\\expe" : "Recognizes e with power as the exponential function. It was translated as a function.",
          "\\iunit" : "Imaginary unit was translated to: I",
          "\\Phi" : "Function without DLMF-Definition. We keep it like it is (but delete prefix \\ if necessary)."
        }
      },
      "numericResults" : {
        "overallResult" : "SKIPPED",
        "numberOfTests" : 0,
        "numberOfFailedTests" : 0,
        "numberOfSuccessfulTests" : 0,
        "numberOfSkippedTests" : 0,
        "numberOfErrorTests" : 0,
        "wasAborted" : false,
        "crashed" : false,
        "testCalculationsGroups" : [ ]
      },
      "symbolicResults" : {
        "overallResult" : "ERROR",
        "numberOfTests" : 1,
        "numberOfFailedTests" : 0,
        "numberOfSuccessfulTests" : 0,
        "numberOfSkippedTests" : 0,
        "numberOfErrorTests" : 1,
        "crashed" : false,
        "testCalculationsGroup" : [ {
          "lhs" : "\\[CapitalPhi]*(z , s , a)",
          "rhs" : "Divide[1,2*(a)^(s)]+Divide[1,(z)^(a)]*Sum[Divide[Exp[- 2*Pi*I*(k - 1)*a]*Gamma[1 - s, a*(- 2*Pi*I*(k - 1)- Log[z])],(- 2*Pi*I*(k - 1)- Log[z])^(1 - s)]+Divide[Exp[2*Pi*I*k*a]*Gamma[1 - s, a*(2*Pi*I*k - Log[z])],(2*Pi*I*k - Log[z])^(1 - s)], {k, 1, Infinity}, GenerateConditions->None]",
          "testExpression" : "(\\[CapitalPhi]*(z , s , a))-(Divide[1,2*(a)^(s)]+Divide[1,(z)^(a)]*Sum[Divide[Exp[- 2*Pi*I*(k - 1)*a]*Gamma[1 - s, a*(- 2*Pi*I*(k - 1)- Log[z])],(- 2*Pi*I*(k - 1)- Log[z])^(1 - s)]+Divide[Exp[2*Pi*I*k*a]*Gamma[1 - s, a*(2*Pi*I*k - Log[z])],(2*Pi*I*k - Log[z])^(1 - s)], {k, 1, Infinity}, GenerateConditions->None])",
          "testCalculations" : [ {
            "result" : "ERROR",
            "testTitle" : "Simple",
            "testExpression" : null,
            "resultExpression" : null,
            "wasAborted" : false,
            "conditionallySuccessful" : false
          } ]
        } ]
      }
    },
    "SymPy" : {
      "translation" : "",
      "translationInformation" : {
        "tokenTranslations" : {
          "Error" : "(LaTeX -> SymPy) No translation possible for given token: Cannot extract information from feature set: \\incGamma [\\incGamma]"
        }
      }
    },
    "Maple" : {
      "translation" : "Phi(z , s , a) = (1)/(2*(a)^(s))+(1)/((z)^(a))*sum((exp(- 2*Pi*I*(k - 1)*a)*GAMMA(1 - s, a*(- 2*Pi*I*(k - 1)- log(z))))/((- 2*Pi*I*(k - 1)- log(z))^(1 - s))+(exp(2*Pi*I*k*a)*GAMMA(1 - s, a*(2*Pi*I*k - log(z))))/((2*Pi*I*k - log(z))^(1 - s)), k = 1..infinity)",
      "translationInformation" : {
        "subEquations" : [ "Phi(z , s , a) = (1)/(2*(a)^(s))+(1)/((z)^(a))*sum((exp(- 2*Pi*I*(k - 1)*a)*GAMMA(1 - s, a*(- 2*Pi*I*(k - 1)- log(z))))/((- 2*Pi*I*(k - 1)- log(z))^(1 - s))+(exp(2*Pi*I*k*a)*GAMMA(1 - s, a*(2*Pi*I*k - log(z))))/((2*Pi*I*k - log(z))^(1 - s)), k = 1..infinity)" ],
        "freeVariables" : [ "Phi", "a", "s", "z" ],
        "tokenTranslations" : {
          "\\cpi" : "Pi was translated to: Pi",
          "\\log" : "Logarithm; Example: \\log@@{z}\nWill be translated to: log($0)\nConstraints: z != 0\nBranch Cuts: (-\\infty, 0]\nRelevant links to definitions:\nDLMF:  http://dlmf.nist.gov/4.2#E2\nMaple: https://www.maplesoft.com/support/help/maple/view.aspx?path=log",
          "\\incGamma" : "Incomplete Gamma function (upper); Example: \\incGamma@{a}{z}\nWill be translated to: GAMMA($0, $1)\nRelevant links to definitions:\nDLMF:  http://dlmf.nist.gov/8.2#E2\nMaple: https://www.maplesoft.com/support/help/maple/view.aspx?path=GAMMA",
          "\\expe" : "Recognizes e with power as the exponential function. It was translated as a function.",
          "\\iunit" : "Imaginary unit was translated to: I",
          "\\Phi" : "Function without DLMF-Definition. We keep it like it is (but delete prefix \\ if necessary)."
        }
      }
    }
  },
  "positions" : [ ],
  "includes" : [ "a", "\\Phi(z,s,a)", "\\Phi(z,s,a)=\\frac{1}{2a^s}+\\frac{1}{z^a}\\sum_{k=1}^\\infty\\frac{e^{-2\\pi i(k-1)a}\\Gamma(1-s,a(-2\\pi i(k-1)-\\log(z)))}     {(-2\\pi i(k-1)-\\log(z))^{1-s}}+\\frac{e^{2\\pi ika}\\Gamma(1-s,a(2\\pi ik-\\log(z)))}{(2\\pi ik-\\log(z))^{1-s}}", "z", "s" ],
  "isPartOf" : [ "\\Phi(z,s,a)=\\frac{1}{2a^s}+\\frac{1}{z^a}\\sum_{k=1}^\\infty\\frac{e^{-2\\pi i(k-1)a}\\Gamma(1-s,a(-2\\pi i(k-1)-\\log(z)))}     {(-2\\pi i(k-1)-\\log(z))^{1-s}}+\\frac{e^{2\\pi ika}\\Gamma(1-s,a(2\\pi ik-\\log(z)))}{(2\\pi ik-\\log(z))^{1-s}}" ],
  "definiens" : [ ]
}

Specify your own input

Formula input
Wikitext context	In [[mathematics]], the '''Lerch [[zeta function]]''', sometimes called the '''Hurwitz–Lerch zeta-function''', is a [[special function]] that generalizes the [[Hurwitz zeta function]] and the [[polylogarithm]]. It is named after the Czech mathematician [[Mathias Lerch]] [http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Lerch.html]. ==Definition== The Lerch zeta function is given by :<math>L(\lambda, \alpha, s) = \sum_{n=0}^\infty \frac { e^{2\pi i\lambda n}} {(n+\alpha)^s}.</math> A related function, the '''Lerch transcendent''', is given by :<math>\Phi(z, s, \alpha) = \sum_{n=0}^\infty \frac { z^n} {(n+\alpha)^s}.</math> The two are related, as :<math>\,\Phi(e^{2\pi i\lambda}, s,\alpha)=L(\lambda, \alpha,s).</math> ==Integral representations== An integral representation is given by :<math> \Phi(z,s,a)=\frac{1}{\Gamma(s)}\int_0^\infty \frac{t^{s-1}e^{-at}}{1-ze^{-t}}\,dt</math> for :<math>\Re(a)>0\wedge\Re(s)>0\wedge z<1\vee\Re(a)>0\wedge\Re(s)>1\wedge z=1. </math> A [[contour integral]] representation is given by :<math> \Phi(z,s,a)=-\frac{\Gamma(1-s)}{2\pi i}\int_0^{(+\infty)} \frac{(-t)^{s-1}e^{-at}}{1-ze^{-t}}\,dt</math> for :<math>\Re(a)>0\wedge\Re(s)<0\wedge z<1</math> where the contour must not enclose any of the points <math>t=\log(z)+2k\pi i,k\in Z.</math> A Hermite-like integral representation is given by :<math> \Phi(z,s,a)= \frac{1}{2a^s}+ \int_0^\infty \frac{z^t}{(a+t)^s}\,dt+ \frac{2}{a^{s-1}} \int_0^\infty \frac{\sin(s\arctan(t)-ta\log(z))}{(1+t^2)^{s/2}(e^{2\pi at}-1)}\,dt </math> for :<math>\Re(a)>0\wedge \|z\|<1 </math> and :<math> \Phi(z,s,a)=\frac{1}{2a^s}+ \frac{\log^{s-1}(1/z)}{z^a}\Gamma(1-s,a\log(1/z))+ \frac{2}{a^{s-1}} \int_0^\infty \frac{\sin(s\arctan(t)-ta\log(z))}{(1+t^2)^{s/2}(e^{2\pi at}-1)}\,dt </math> for :<math>\Re(a)>0. </math> Similar representations include :<math> \Phi(z,s,a)= \frac{1}{2a^s} + \int_{0}^{\infty}\frac{\cos(t\log z)\sin\Big(s\arctan\tfrac{t}{a}\Big) - \sin(t\log z)\cos\Big(s\arctan\tfrac{t}{a}\Big)}{\big(a^2 + t^2\big)^{\frac{s}{2}} \tanh\pi t }\,dt, </math> and :<math> \Phi(-z,s,a)= \frac{1}{2a^s} + \int_{0}^{\infty}\frac{\cos(t\log z)\sin\Big(s\arctan\tfrac{t}{a}\Big) - \sin(t\log z)\cos\Big(s\arctan\tfrac{t}{a}\Big)}{\big(a^2 + t^2\big)^{\frac{s}{2}} \sinh\pi t }\,dt, </math> holding for positive ''z'' (and more generally wherever the integrals converge). Furthermore, :<math> \Phi(e^{i\varphi},s,a)=L\big(\tfrac{\varphi}{2\pi},a,s\big)= \frac{1}{a^s} + \frac{1}{2\Gamma(s)}\int_{0}^{\infty}\frac{t^{s-1}e^{-at}\big(e^{i\varphi}-e^{-t}\big)}{\cosh{t}-\cos{\varphi}}\,dt, </math> The last formula is also known as ''Lipschitz formula''. ==Special cases== The [[Hurwitz zeta function]] is a special case, given by :<math>\,\zeta(s,\alpha)=L(0, \alpha,s)=\Phi(1,s,\alpha).</math> The [[polylogarithm]] is a special case of the Lerch Zeta, given by :<math>\,\textrm{Li}_s(z)=z\Phi(z,s,1).</math> The [[Legendre chi function]] is a special case, given by :<math>\,\chi_n(z)=2^{-n}z \Phi (z^2,n,1/2).</math> The [[Riemann zeta function]] is given by :<math>\,\zeta(s)=\Phi (1,s,1).</math> The [[Dirichlet eta function]] is given by :<math>\,\eta(s)=\Phi (-1,s,1).</math> ==Identities== For λ rational, the summand is a [[root of unity]], and thus <math>L(\lambda, \alpha, s)</math> may be expressed as a finite sum over the Hurwitz zeta-function. Suppose <math>\lambda = \frac{p}{q}</math> with <math>p, q \in \mathbb{Z}</math> and <math>q > 0</math>. Then <math>z = \omega = e^{2 \pi i \frac{p}{q}}</math> and <math>\omega^q = 1</math>. :<math>\Phi(\omega, s, \alpha) = \sum_{n=0}^\infty \frac {\omega^n} {(n+\alpha)^s} = \sum_{m=0}^{q-1} \sum_{n=0}^\infty \frac {\omega^{qn + m}}{(qn + m + \alpha)^s} = \sum_{m=0}^{q-1} \omega^m q^{-s} \zeta(s,\frac{m + \alpha}{q})</math> Various identities include: :<math>\Phi(z,s,a)=z^n \Phi(z,s,a+n) + \sum_{k=0}^{n-1} \frac {z^k}{(k+a)^s}</math> and :<math>\Phi(z,s-1,a)=\left(a+z\frac{\partial}{\partial z}\right) \Phi(z,s,a)</math> and :<math>\Phi(z,s+1,a)=-\,\frac{1}{s}\frac{\partial}{\partial a} \Phi(z,s,a).</math> ==Series representations== A series representation for the Lerch transcendent is given by :<math>\Phi(z,s,q)=\frac{1}{1-z} \sum_{n=0}^\infty \left(\frac{-z}{1-z} \right)^n \sum_{k=0}^n (-1)^k \binom{n}{k} (q+k)^{-s}.</math> (Note that <math>\tbinom{n}{k}</math> is a [[binomial coefficient]].) The series is valid for all ''s'', and for complex ''z'' with Re(''z'')<1/2. Note a general resemblance to a similar series representation for the Hurwitz zeta function. <ref name="benorin"> {{cite web \| url=https://www.physicsforums.com/insights/the-analytic-continuation-of-the-lerch-and-the-zeta-functions/ \| title=The Analytic Continuation of the Lerch Transcendent and the Riemann Zeta Function \| access-date=28 April 2020 }} </ref> A [[Taylor series]] in the first parameter was given by [[Arthur Erdélyi\|Erdélyi]]. It may be written as the following series, which is valid for :<math>\|\log(z)\|<2 \pi;s\neq 1,2,3,\dots; a\neq 0,-1,-2,\dots</math> :<math> \Phi(z,s,a)=z^{-a}\left[\Gamma(1-s)\left(-\log (z)\right)^{s-1} +\sum_{k=0}^\infty \zeta(s-k,a)\frac{\log^k (z)}{k!}\right] </math> {{cite journal\|author=B. R. Johnson\|title=Generalized Lerch zeta-function\|journal=Pacific J. Math.\|volume=53\|number=1\|date=1974\|pages=189–193\|doi=10.2140/pjm.1974.53.189\|doi-access=free}} If n is a positive integer, then :<math> \Phi(z,n,a)=z^{-a}\left\{ \sum_{{k=0}\atop k\neq n-1}^ \infty \zeta(n-k,a)\frac{\log^k (z)}{k!} +\left[\psi(n)-\psi(a)-\log(-\log(z))\right]\frac{\log^{n-1}(z)}{(n-1)!}\right\}, </math> where <math>\psi(n)</math> is the [[digamma function]]. A [[Taylor series]] in the third variable is given by :<math> \Phi(z,s,a+x)=\sum_{k=0}^\infty \Phi(z,s+k,a)(s)_{k}\frac{(-x)^k}{k!};\|x\|<\Re(a), </math> where <math>(s)_{k}</math> is the [[Pochhammer symbol]]. Series at ''a'' = -''n'' is given by :<math> \Phi(z,s,a)=\sum_{k=0}^n \frac{z^k}{(a+k)^s} +z^n\sum_{m=0}^\infty (1-m-s)_{m}\operatorname{Li}_{s+m}(z)\frac{(a+n)^m}{m!};\ a\rightarrow-n </math> A special case for ''n'' = 0 has the following series :<math> \Phi(z,s,a)=\frac{1}{a^s} +\sum_{m=0}^\infty (1-m-s)_m \operatorname{Li}_{s+m}(z)\frac{a^m}{m!}; \|a\|<1, </math> where <math>\operatorname{Li}_s(z)</math> is the [[polylogarithm]]. An [[asymptotic series]] for <math>s\rightarrow-\infty</math> :<math> \Phi(z,s,a)=z^{-a}\Gamma(1-s)\sum_{k=-\infty}^\infty [2k\pi i-\log(z)]^{s-1}e^{2k\pi ai} </math> for <math>\|a\|<1;\Re(s)<0 ;z\notin (-\infty,0) </math> and :<math> \Phi(-z,s,a)=z^{-a}\Gamma(1-s)\sum_{k=-\infty}^\infty [(2k+1)\pi i-\log(z)]^{s-1}e^{(2k+1)\pi ai} </math> for <math>\|a\|<1;\Re(s)<0 ;z\notin (0,\infty). </math> An asymptotic series in the [[incomplete gamma function]] :<math> \Phi(z,s,a)=\frac{1}{2a^s}+ \frac{1}{z^a}\sum_{k=1}^\infty \frac{e^{-2\pi i(k-1)a}\Gamma(1-s,a(-2\pi i(k-1)-\log(z)))} {(-2\pi i(k-1)-\log(z))^{1-s}}+ \frac{e^{2\pi ika}\Gamma(1-s,a(2\pi ik-\log(z)))}{(2\pi ik-\log(z))^{1-s}} </math> for <math>\|a\|<1;\Re(s)<0.</math> == Asymptotic expansion == The polylogarithm function <math>\mathrm{Li}_n(z)</math> is defined as :<math> \mathrm{Li}_0(z)=\frac{z}{1-z}, \qquad \mathrm{Li}_{-n}(z)=z \frac{d}{dz} \mathrm{Li}_{1-n}(z). </math> Let :<math> \Omega_{a} \equiv \begin{cases} \mathbb{C}\setminus[1,\infty) & \text{if } \Re a > 0, \\ {z \in \mathbb{C}, \|z\|<1} & \text{if } \Re a \le 0. \end{cases} </math> For <math>\|\mathrm{Arg}(a)\|<\pi, s \in \mathbb{C}</math> and <math>z \in \Omega_{a}</math>, an asymptotic expansion of <math>\Phi(z,s,a)</math> for large <math>a</math> and fixed <math>s</math> and <math>z</math> is given by :<math> \Phi(z,s,a) = \frac{1}{1-z} \frac{1}{a^{s}} + \sum_{n=1}^{N-1} \frac{(-1)^{n} \mathrm{Li}_{-n}(z)}{n!} \frac{(s)_{n}}{a^{n+s}} +O(a^{-N-s}) </math> for <math>N \in \mathbb{N}</math>, where <math>(s)_n = s (s+1)\cdots (s+n-1)</math> is the [[Falling and rising factorials\|Pochhammer symbol]].<ref>{{cite journal \|last1=Ferreira \|first1=Chelo \|last2=López \|first2=José L. \|title=Asymptotic expansions of the Hurwitz–Lerch zeta function \|journal=Journal of Mathematical Analysis and Applications \|date=October 2004 \|volume=298 \|issue=1 \|pages=210–224 \|doi=10.1016/j.jmaa.2004.05.040}}</ref> Let :<math> f(z,x,a) \equiv \frac{1-(z e^{-x})^{1-a}}{1-z e^{-x}}. </math> Let <math>C_{n}(z,a)</math> be its Taylor coefficients at <math>x=0</math>. Then for fixed <math>N \in \mathbb{N}, \Re a > 1</math> and <math>\Re s > 0</math>, :<math> \Phi(z,s,a) - \frac{\mathrm{Li}_{s}(z)}{z^{a}} = \sum_{n=0}^{N-1} C_{n}(z,a) \frac{(s)_{n}}{a^{n+s}} + O\left( (\Re a)^{1-N-s}+a z^{-\Re a} \right), </math> as <math>\Re a \to \infty</math>.<ref>{{cite journal \|last1=Cai \|first1=Xing Shi \|last2=López \|first2=José L. \|title=A note on the asymptotic expansion of the Lerch's transcendent \|journal=Integral Transforms and Special Functions \|date=10 June 2019 \|volume=30 \|issue=10 \|pages=844–855 \|doi=10.1080/10652469.2019.1627530\|arxiv=1806.01122 \|s2cid=119619877 }}</ref> ==Software== The Lerch transcendent is implemented as LerchPhi in [http://www.maplesoft.com/support/help/Maple/view.aspx?path=LerchPhi Maple] and [https://functions.wolfram.com/ZetaFunctionsandPolylogarithms/LerchPhi/ Mathematica], and as lerchphi in [http://mpmath.org/doc/current/functions/zeta.html#lerch-transcendent mpmath] and [https://docs.sympy.org/latest/modules/functions/special.html#sympy.functions.special.zeta_functions.lerchphi SymPy]. ==References== {{Reflist}} * {{dlmf \| id= 25.14 \| first= T. M. \| last= Apostol \| title= Lerch's Transcendent}}. * {{citation \| first1= H. \| last1= Bateman \| author1-link= Harry Bateman \| first2= A. \| last2= Erdélyi \| author2-link= Arthur Erdélyi \| title= Higher Transcendental Functions, Vol. I \| year= 1953 \| location= New York \| publisher= McGraw-Hill \| url=http://apps.nrbook.com/bateman/Vol1.pdf}}. (See § 1.11, "The function Ψ(''z'',''s'',''v'')", p. 27) * {{cite book \|author-first1=Izrail Solomonovich \|author-last1=Gradshteyn \|author-link1=Izrail Solomonovich Gradshteyn \|author-first2=Iosif Moiseevich \|author-last2=Ryzhik \|author-link2=Iosif Moiseevich Ryzhik \|author-first3=Yuri Veniaminovich \|author-last3=Geronimus \|author-link3=Yuri Veniaminovich Geronimus \|author-first4=Michail Yulyevich \|author-last4=Tseytlin \|author-link4=Michail Yulyevich Tseytlin \|author-first5=Alan \|author-last5=Jeffrey \|editor-first1=Daniel \|editor-last1=Zwillinger \|editor-first2=Victor Hugo \|editor-last2=Moll \|translator=Scripta Technica, Inc. \|title=Table of Integrals, Series, and Products \|publisher=Academic Press \|date=2015 \|orig-year=October 2014 \|edition=8 \|language=English \|isbn=978-0-12-384933-5 \|lccn=2014010276 <!-- \|url=https://books.google.com/books?id=NjnLAwAAQBAJ \|access-date=2016-02-21-->\|title-link=Gradshteyn and Ryzhik \|chapter=9.55.}} * {{citation \| first1= Jesus \| last1= Guillera \| first2= Jonathan \| last2= Sondow \| arxiv= math.NT/0506319 \| mr = 2429900 \| title= Double integrals and infinite products for some classical constants via analytic continuations of Lerch's transcendent \| journal= The Ramanujan Journal \| volume= 16 \| year= 2008 \| pages= 247–270 \| issue= 3 \| doi= 10.1007/s11139-007-9102-0\| s2cid= 119131640 }}. (Includes various basic identities in the introduction.) * {{citation \| first= M. \| last= Jackson \| title= On Lerch's transcendent and the basic bilateral hypergeometric series <sub>2</sub>''ψ''<sub>2</sub> \| year= 1950 \| journal= J. London Math. Soc. \| volume= 25 \| issue= 3 \| pages= 189–196 \| doi= 10.1112/jlms/s1-25.3.189 \| mr= 0036882}}. * {{citation \| first1= F. \| last1= Johansson \| first2= Ia. \| last2= Blagouchine \| arxiv= 1804.01679 \| mr = 3925487 \| title= Computing Stieltjes constants using complex integration \| journal= Mathematics of Computation \| volume= 88 \| year= 2019 \| pages= 1829–1850 \| issue= 318 \| doi= 10.1090/mcom/3401\| s2cid= 4619883 }}. * {{citation \| first1= Antanas \| last1= Laurinčikas \| first2= Ramūnas \| last2= Garunkštis \| title= The Lerch zeta-function \| publisher= Kluwer Academic Publishers \| location= Dordrecht \| year= 2002 \| isbn= 978-1-4020-1014-9 \| mr= 1979048}}. * {{citation \| first= Mathias \| last= Lerch \| authorlink= Mathias Lerch \| title= Note sur la fonction <math>\scriptstyle{\mathfrak K}(w,x,s) = \sum_{k=0}^\infty {e^{2k\pi ix} \over (w+k)^s}</math> \| language= French \| year= 1887 \| journal= Acta Mathematica \| volume= 11 \| issue= 1–4 \| pages= 19–24 \| doi= 10.1007/BF02612318 \| mr= 1554747 \| jfm= 19.0438.01\| s2cid= 121885446 \| url= https://zenodo.org/record/1681743 \| doi-access= free }}. ==External links== * {{citation \| first1= Sergej V. \| last1= Aksenov \| first2= Ulrich D. \| last2= Jentschura \| year=2002 \| url= http://aksenov.freeshell.org/lerchphi.html \| title= C and Mathematica Programs for Calculation of Lerch's Transcendent}}. * Ramunas Garunkstis, ''[http://www.mif.vu.lt/~garunkstis Home Page]'' (2005) ''(Provides numerous references and preprints.)'' * Ramunas Garunkstis, ''[http://www.mif.vu.lt/~garunkstis/preprintai/approx.pdf Approximation of the Lerch Zeta Function]'' (PDF) * S. Kanemitsu, Y. Tanigawa and H. Tsukada, ''[http://www.iisc.ernet.in/nias/HRJ/vol27/Ktt.pdf A generalization of Bochner's formula]{{dead link\|date=December 2017 \|bot=InternetArchiveBot \|fix-attempted=yes }}'', (undated, 2005 or earlier) * {{MathWorld \| urlname= LerchTranscendent \| title= Lerch Transcendent}} * {{cite web \| url= http://dlmf.nist.gov/25.14 \|title= §25.14, Lerch's Transcendent \|date= 2010 \|work= NIST Digital Library of Mathematical Functions \|publisher= National Institute of Standards and Technology \|accessdate= 28 January 2012 }} [[Category:Zeta and L-functions]]
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