The q-derivative and q-integral

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The q-derivative and q-integral

π’Ÿ q ⁒ f ⁒ ( z ) := { f ⁒ ( z ) - f ⁒ ( q ⁒ z ) ( 1 - q ) ⁒ z , z β‰  0 f β€² ⁒ ( 0 ) , z = 0 . assign q-derivative π‘ž 𝑓 𝑧 cases 𝑓 𝑧 𝑓 π‘ž 𝑧 1 π‘ž 𝑧 𝑧 0 superscript 𝑓 β€² 0 𝑧 0 {\displaystyle{\displaystyle{\displaystyle{}\mathcal{D}_{q}f(z):=\left\{\begin% {array}[]{ll}\displaystyle\frac{f(z)-f(qz)}{(1-q)z},&z\neq 0\\ f^{\prime}(0),&z=0.\end{array}\right.}}} {\displaystyle \index{q-Derivative operator@$q$-Derivative operator} \qderiv{q}f(z):=\left\{\begin{array}{ll} \displaystyle \frac{f(z)-f(qz)}{(1-q)z}, & z\neq 0\[5mm] f'(0), & z=0.\end{array}\right. }
π’Ÿ q 0 ⁒ f := f   and   π’Ÿ q n ⁒ f := π’Ÿ q ⁑ ( π’Ÿ q n - 1 ⁒ f )   n = 1 , 2 , 3 , … formulae-sequence assign q-derivative 0 π‘ž 𝑓 𝑓 and formulae-sequence assign q-derivative 𝑛 π‘ž 𝑓 q-derivative π‘ž q-derivative 𝑛 1 π‘ž 𝑓 𝑛 1 2 3 … {\displaystyle{\displaystyle{\displaystyle\mathcal{D}^{0}_{q}f:=f\quad\textrm{% and}\quad\mathcal{D}^{n}_{q}f:=\mathcal{D}_{q}\left(\mathcal{D}^{n-1}_{q}f% \right)\quad n=1,2,3,\ldots}}} {\displaystyle \qderiv[0]{q}f:=f\quad\textrm{and}\quad \qderiv[n]{q}f:=\qderiv{q}@{\qderiv[n-1]{q}f} \quad n=1,2,3,\ldots }
lim q β†’ 1 ⁑ π’Ÿ q ⁒ f ⁒ ( z ) = f β€² ⁒ ( z ) subscript β†’ π‘ž 1 q-derivative π‘ž 𝑓 𝑧 superscript 𝑓 β€² 𝑧 {\displaystyle{\displaystyle{\displaystyle\lim\limits_{q\rightarrow 1}\mathcal% {D}_{q}f(z)=f^{\prime}(z)}}} {\displaystyle \lim\limits_{q\rightarrow 1}\qderiv{q}f(z)=f'(z) }
π’Ÿ q ⁑ ( f ⁒ ( Ξ³ ⁒ x ) ) = Ξ³ ⁒ ( π’Ÿ q ⁒ f ) ⁒ ( Ξ³ ⁒ x ) q-derivative π‘ž 𝑓 𝛾 π‘₯ 𝛾 q-derivative π‘ž 𝑓 𝛾 π‘₯ {\displaystyle{\displaystyle{\displaystyle\mathcal{D}_{q}\left(f(\gamma x)% \right)=\gamma\left(\mathcal{D}_{q}f\right)(\gamma x)}}} {\displaystyle \qderiv{q}@{f(\gamma x)}=\gamma\left(\qderiv{q}f\right)(\gamma x) }
π’Ÿ q n ⁑ ( f ⁒ ( Ξ³ ⁒ x ) ) = Ξ³ n ⁒ ( π’Ÿ q n ⁒ f ) ⁒ ( Ξ³ ⁒ x ) q-derivative 𝑛 π‘ž 𝑓 𝛾 π‘₯ superscript 𝛾 𝑛 q-derivative 𝑛 π‘ž 𝑓 𝛾 π‘₯ {\displaystyle{\displaystyle{\displaystyle\mathcal{D}^{n}_{q}\left(f(\gamma x)% \right)=\gamma^{n}\left(\mathcal{D}^{n}_{q}f\right)(\gamma x)}}} {\displaystyle \qderiv[n]{q}@{f(\gamma x)}=\gamma^n\left(\qderiv[n]{q}f\right)(\gamma x) }

Constraint(s): n = 0 , 1 , 2 , … 𝑛 0 1 2 … {\displaystyle{\displaystyle{\displaystyle n=0,1,2,\ldots}}}


π’Ÿ q ⁑ ( f ⁒ ( x ) ⁒ g ⁒ ( x ) ) = f ⁒ ( q ⁒ x ) ⁒ π’Ÿ q ⁒ g ⁒ ( x ) + g ⁒ ( x ) ⁒ π’Ÿ q ⁒ f ⁒ ( x ) q-derivative π‘ž 𝑓 π‘₯ 𝑔 π‘₯ 𝑓 π‘ž π‘₯ q-derivative π‘ž 𝑔 π‘₯ 𝑔 π‘₯ q-derivative π‘ž 𝑓 π‘₯ {\displaystyle{\displaystyle{\displaystyle\mathcal{D}_{q}\left(f(x)g(x)\right)% =f(qx)\mathcal{D}_{q}g(x)+g(x)\mathcal{D}_{q}f(x)}}} {\displaystyle \qderiv{q}@{f(x)g(x)}= f(qx)\qderiv{q}g(x)+g(x)\qderiv{q}f(x) }
π’Ÿ q n ⁑ ( f ⁒ ( x ) ⁒ g ⁒ ( x ) ) = βˆ‘ k = 0 n [ n k ] q ⁒ ( π’Ÿ q n - k ⁒ f ) ⁒ ( q k ⁒ x ) ⁒ ( π’Ÿ q k ⁒ g ) ⁒ ( x ) q-derivative 𝑛 π‘ž 𝑓 π‘₯ 𝑔 π‘₯ superscript subscript π‘˜ 0 𝑛 q-binomial 𝑛 π‘˜ π‘ž q-derivative 𝑛 π‘˜ π‘ž 𝑓 superscript π‘ž π‘˜ π‘₯ q-derivative π‘˜ π‘ž 𝑔 π‘₯ {\displaystyle{\displaystyle{\displaystyle\mathcal{D}^{n}_{q}\left(f(x)g(x)% \right)=\sum_{k=0}^{n}\genfrac{[}{]}{0.0pt}{}{n}{k}_{q}\left(\mathcal{D}^{n-k}% _{q}f\right)(q^{k}x)\left(\mathcal{D}^{k}_{q}g\right)(x)}}} {\displaystyle \qderiv[n]{q}@{f(x)g(x)}=\sum_{k=0}^n\qBinomial{n}{k}{q} \left(\qderiv[n-k]{q}f\right)(q^kx)\left(\qderiv[k]{q}g\right)(x) }

Constraint(s): n = 0 , 1 , 2 , … 𝑛 0 1 2 … {\displaystyle{\displaystyle{\displaystyle n=0,1,2,\ldots}}}


∫ 0 z f ⁒ ( t ) ⁒ d q ⁒ t := z ⁒ ( 1 - q ) ⁒ βˆ‘ n = 0 ∞ f ⁒ ( q n ⁒ z ) ⁒ q n assign superscript subscript 0 𝑧 𝑓 𝑑 subscript 𝑑 π‘ž 𝑑 𝑧 1 π‘ž superscript subscript 𝑛 0 𝑓 superscript π‘ž 𝑛 𝑧 superscript π‘ž 𝑛 {\displaystyle{\displaystyle{\displaystyle{}{}\int_{0}^{z}f(t)\,d_{q}t:=z(1-q)% \sum_{n=0}^{\infty}f(q^{n}z)q^{n}}}} {\displaystyle \index{q-Integral@$q$-Integral}\index{Jackson-Thomae q-integral@Jackson-Thomae $q$-integral} \int_0^zf(t)\,d_qt:=z(1-q)\sum_{n=0}^{\infty}f(q^nz)q^n }

Constraint(s): 0 < q < 1 0 π‘ž 1 {\displaystyle{\displaystyle{\displaystyle 0<q<1}}}


∫ 0 ∞ f ⁒ ( t ) ⁒ d q ⁒ t := ( 1 - q ) ⁒ βˆ‘ n = - ∞ ∞ f ⁒ ( q n ) ⁒ q n assign superscript subscript 0 𝑓 𝑑 subscript 𝑑 π‘ž 𝑑 1 π‘ž superscript subscript 𝑛 𝑓 superscript π‘ž 𝑛 superscript π‘ž 𝑛 {\displaystyle{\displaystyle{\displaystyle\int_{0}^{\infty}f(t)\,d_{q}t:=(1-q)% \sum_{n=-\infty}^{\infty}f(q^{n})q^{n}}}} {\displaystyle \int_0^{\infty}f(t)\,d_qt:=(1-q)\sum_{n=-\infty}^{\infty}f(q^n)q^n }

Constraint(s): 0 < q < 1 0 π‘ž 1 {\displaystyle{\displaystyle{\displaystyle 0<q<1}}}


lim q β†’ 1 ⁑ ∫ 0 z f ⁒ ( t ) ⁒ d q ⁒ t = ∫ 0 z f ⁒ ( t ) ⁒ 𝑑 t subscript β†’ π‘ž 1 superscript subscript 0 𝑧 𝑓 𝑑 subscript 𝑑 π‘ž 𝑑 superscript subscript 0 𝑧 𝑓 𝑑 differential-d 𝑑 {\displaystyle{\displaystyle{\displaystyle\lim\limits_{q\rightarrow 1}\int_{0}% ^{z}f(t)\,d_{q}t=\int_{0}^{z}f(t)\,dt}}} {\displaystyle \lim\limits_{q\rightarrow 1}\int_0^zf(t)\,d_qt=\int_0^zf(t)\,dt }
∫ a b f ⁒ ( t ) ⁒ d q ⁒ t = b ⁒ ( 1 - q ) ⁒ βˆ‘ n = 0 ∞ f ⁒ ( b ⁒ q n ) ⁒ q n - a ⁒ ( 1 - q ) ⁒ βˆ‘ n = 0 ∞ f ⁒ ( a ⁒ q n ) ⁒ q n superscript subscript π‘Ž 𝑏 𝑓 𝑑 subscript 𝑑 π‘ž 𝑑 𝑏 1 π‘ž superscript subscript 𝑛 0 𝑓 𝑏 superscript π‘ž 𝑛 superscript π‘ž 𝑛 π‘Ž 1 π‘ž superscript subscript 𝑛 0 𝑓 π‘Ž superscript π‘ž 𝑛 superscript π‘ž 𝑛 {\displaystyle{\displaystyle{\displaystyle\int_{a}^{b}f(t)\,d_{q}t=b(1-q)\sum_% {n=0}^{\infty}f(bq^{n})q^{n}-a(1-q)\sum_{n=0}^{\infty}f(aq^{n})q^{n}}}} {\displaystyle \int_a^bf(t)\,d_qt=b(1-q)\sum_{n=0}^{\infty}f(bq^n)q^n-a(1-q)\sum_{n=0}^{\infty}f(aq^n)q^n }

Constraint(s): 0 < q < 1 0 π‘ž 1 {\displaystyle{\displaystyle{\displaystyle 0<q<1}}}


∫ - ∞ ∞ f ⁒ ( t ) ⁒ d q ⁒ t = ( 1 - q ) ⁒ βˆ‘ n = - ∞ ∞ { f ⁒ ( q n ) + f ⁒ ( - q n ) } ⁒ q n superscript subscript 𝑓 𝑑 subscript 𝑑 π‘ž 𝑑 1 π‘ž superscript subscript 𝑛 𝑓 superscript π‘ž 𝑛 𝑓 superscript π‘ž 𝑛 superscript π‘ž 𝑛 {\displaystyle{\displaystyle{\displaystyle\int_{-\infty}^{\infty}f(t)\,d_{q}t=% (1-q)\sum_{n=-\infty}^{\infty}\left\{f(q^{n})+f(-q^{n})\right\}q^{n}}}} {\displaystyle \int_{-\infty}^{\infty}f(t)\,d_qt=(1-q)\sum_{n=-\infty}^{\infty}\left\{f(q^n)+f(-q^n)\right\}q^n }

Constraint(s): 0 < q < 1 0 π‘ž 1 {\displaystyle{\displaystyle{\displaystyle 0<q<1}}}


F ⁒ ( z ) = ∫ 0 z f ⁒ ( t ) ⁒ d q ⁒ t   ⟹   π’Ÿ q ⁒ F ⁒ ( z ) = f ⁒ ( z ) formulae-sequence 𝐹 𝑧 superscript subscript 0 𝑧 𝑓 𝑑 subscript 𝑑 π‘ž 𝑑 ⟹ q-derivative π‘ž 𝐹 𝑧 𝑓 𝑧 {\displaystyle{\displaystyle{\displaystyle F(z)=\int_{0}^{z}f(t)\,d_{q}t\quad% \Longrightarrow\quad\mathcal{D}_{q}F(z)=f(z)}}} {\displaystyle F(z)=\int_0^zf(t)\,d_qt\quad\Longrightarrow\quad\qderiv{q}F(z)=f(z) }
∫ a b π’Ÿ q ⁒ f ⁒ ( t ) ⁒ d q ⁒ t = f ⁒ ( b ) - f ⁒ ( a ) superscript subscript π‘Ž 𝑏 q-derivative π‘ž 𝑓 𝑑 subscript 𝑑 π‘ž 𝑑 𝑓 𝑏 𝑓 π‘Ž {\displaystyle{\displaystyle{\displaystyle\int_{a}^{b}\mathcal{D}_{q}f(t)\,d_{% q}t=f(b)-f(a)}}} {\displaystyle \int_a^b\qderiv{q}f(t)\,d_qt=f(b)-f(a) }
∫ a b g ⁒ ( x ) ⁒ π’Ÿ q ⁒ f ⁒ ( x ) ⁒ d q ⁒ x = [ f ⁒ ( x ) ⁒ g ⁒ ( x ) ] a b - ∫ a b f ⁒ ( q ⁒ x ) ⁒ π’Ÿ q ⁒ g ⁒ ( x ) ⁒ d q ⁒ x superscript subscript π‘Ž 𝑏 𝑔 π‘₯ q-derivative π‘ž 𝑓 π‘₯ subscript 𝑑 π‘ž π‘₯ superscript subscript delimited-[] 𝑓 π‘₯ 𝑔 π‘₯ π‘Ž 𝑏 superscript subscript π‘Ž 𝑏 𝑓 π‘ž π‘₯ q-derivative π‘ž 𝑔 π‘₯ subscript 𝑑 π‘ž π‘₯ {\displaystyle{\displaystyle{\displaystyle\int_{a}^{b}g(x)\mathcal{D}_{q}f(x)% \,d_{q}x=\Big{[}f(x)g(x)\Big{]}_{a}^{b}-\int_{a}^{b}f(qx)\mathcal{D}_{q}g(x)\,% d_{q}x}}} {\displaystyle \int_a^bg(x)\qderiv{q}f(x)\,d_qx=\Big[f(x)g(x)\Big]_a^b-\int_a^bf(qx)\qderiv{q}g(x)\,d_qx }
∫ a b ( a - 1 ⁒ q ⁒ t , b - 1 ⁒ q ⁒ t , c ⁒ t ; q ) ∞ ( d ⁒ t , e ⁒ t , f ⁒ t ; q ) ∞ ⁒ d q ⁒ t = ( b - a ) ⁒ ( 1 - q ) ⁒ ( q , a - 1 ⁒ b ⁒ q , a ⁒ b - 1 ⁒ q , c ⁒ d - 1 , c ⁒ e - 1 , c ⁒ f - 1 ; q ) ∞ ( a ⁒ d , a ⁒ e , a ⁒ f , b ⁒ d , b ⁒ e , b ⁒ f ; q ) ∞ superscript subscript π‘Ž 𝑏 q-Pochhammer-symbol superscript π‘Ž 1 π‘ž 𝑑 superscript 𝑏 1 π‘ž 𝑑 𝑐 𝑑 π‘ž q-Pochhammer-symbol 𝑑 𝑑 𝑒 𝑑 𝑓 𝑑 π‘ž subscript 𝑑 π‘ž 𝑑 𝑏 π‘Ž 1 π‘ž q-Pochhammer-symbol π‘ž superscript π‘Ž 1 𝑏 π‘ž π‘Ž superscript 𝑏 1 π‘ž 𝑐 superscript 𝑑 1 𝑐 1 𝑐 superscript 𝑓 1 π‘ž q-Pochhammer-symbol π‘Ž 𝑑 π‘Ž 𝑒 π‘Ž 𝑓 𝑏 𝑑 𝑏 𝑒 𝑏 𝑓 π‘ž {\displaystyle{\displaystyle{\displaystyle\int_{a}^{b}\frac{\left(a^{-1}qt,b^{% -1}qt,ct;q\right)_{\infty}}{\left(dt,et,ft;q\right)_{\infty}}\,d_{q}t{}=(b-a)(% 1-q)\,\frac{\left(q,a^{-1}bq,ab^{-1}q,cd^{-1},c{\mathrm{e}^{-1}},cf^{-1};q% \right)_{\infty}}{\left(ad,ae,af,bd,be,bf;q\right)_{\infty}}}}} {\displaystyle \int_a^b\frac{\qPochhammer{a^{-1}qt,b^{-1}qt,ct}{q}{\infty}}{\qPochhammer{dt,et,ft}{q}{\infty}}\,d_qt {}=(b-a)(1-q)\,\frac{\qPochhammer{q,a^{-1}bq,ab^{-1}q,cd^{-1},c\expe^{-1},cf^{-1}}{q}{\infty}} {\qPochhammer{ad,ae,af,bd,be,bf}{q}{\infty}} }
∫ a b ( a - 1 ⁒ q ⁒ t , b - 1 ⁒ q ⁒ t ; q ) ∞ ( d ⁒ t , e ⁒ t ; q ) ∞ ⁒ d q ⁒ t = ( b - a ) ⁒ ( 1 - q ) ⁒ ( q , a - 1 ⁒ b ⁒ q , a ⁒ b - 1 ⁒ q , a ⁒ b ⁒ d ⁒ e ; q ) ∞ ( a ⁒ d , a ⁒ e , b ⁒ d , b ⁒ e ; q ) ∞ superscript subscript π‘Ž 𝑏 q-Pochhammer-symbol superscript π‘Ž 1 π‘ž 𝑑 superscript 𝑏 1 π‘ž 𝑑 π‘ž q-Pochhammer-symbol 𝑑 𝑑 𝑒 𝑑 π‘ž subscript 𝑑 π‘ž 𝑑 𝑏 π‘Ž 1 π‘ž q-Pochhammer-symbol π‘ž superscript π‘Ž 1 𝑏 π‘ž π‘Ž superscript 𝑏 1 π‘ž π‘Ž 𝑏 𝑑 𝑒 π‘ž q-Pochhammer-symbol π‘Ž 𝑑 π‘Ž 𝑒 𝑏 𝑑 𝑏 𝑒 π‘ž {\displaystyle{\displaystyle{\displaystyle\int_{a}^{b}\frac{\left(a^{-1}qt,b^{% -1}qt;q\right)_{\infty}}{\left(dt,et;q\right)_{\infty}}\,d_{q}t=(b-a)(1-q)\,% \frac{\left(q,a^{-1}bq,ab^{-1}q,abde;q\right)_{\infty}}{\left(ad,ae,bd,be;q% \right)_{\infty}}}}} {\displaystyle \int_a^b\frac{\qPochhammer{a^{-1}qt,b^{-1}qt}{q}{\infty}}{\qPochhammer{dt,et}{q}{\infty}}\,d_qt =(b-a)(1-q)\,\frac{\qPochhammer{q,a^{-1}bq,ab^{-1}q,abde}{q}{\infty}}{\qPochhammer{ad,ae,bd,be}{q}{\infty}} }
∫ a ∞ ( a - 1 ⁒ q ⁒ t ; q ) ∞ ( d ⁒ t , e ⁒ t ; q ) ∞ ⁒ d q ⁒ t = ( 1 - q ) ⁒ ( q , a , a - 1 ⁒ q , a ⁒ d ⁒ e , a - 1 ⁒ d - 1 ⁒ e - 1 ⁒ q ; q ) ∞ ( a ⁒ d , a ⁒ e , d , d - 1 ⁒ q , e , e - 1 ⁒ q ; q ) ∞ superscript subscript π‘Ž q-Pochhammer-symbol superscript π‘Ž 1 π‘ž 𝑑 π‘ž q-Pochhammer-symbol 𝑑 𝑑 𝑒 𝑑 π‘ž subscript 𝑑 π‘ž 𝑑 1 π‘ž q-Pochhammer-symbol π‘ž π‘Ž superscript π‘Ž 1 π‘ž π‘Ž 𝑑 𝑒 superscript π‘Ž 1 superscript 𝑑 1 1 π‘ž π‘ž q-Pochhammer-symbol π‘Ž 𝑑 π‘Ž 𝑒 𝑑 superscript 𝑑 1 π‘ž 𝑒 1 π‘ž π‘ž {\displaystyle{\displaystyle{\displaystyle\int_{a}^{\infty}\frac{\left(a^{-1}% qt;q\right)_{\infty}}{\left(dt,et;q\right)_{\infty}}\,d_{q}t=(1-q)\,\frac{% \left(q,a,a^{-1}q,ade,a^{-1}d^{-1}{\mathrm{e}^{-1}}q;q\right)_{\infty}}{\left(% ad,ae,d,d^{-1}q,e,{\mathrm{e}^{-1}}q;q\right)_{\infty}}}}} {\displaystyle \int_a^{\infty}\frac{\qPochhammer{a^{-1}qt}{q}{\infty}}{\qPochhammer{dt,et}{q}{\infty}}\,d_qt =(1-q)\,\frac{\qPochhammer{q,a,a^{-1}q,ade,a^{-1}d^{-1}\expe^{-1}q}{q}{\infty}} {\qPochhammer{ad,ae,d,d^{-1}q,e,\expe^{-1}q}{q}{\infty}} }
∫ - ∞ ∞ 1 ( d ⁒ t , e ⁒ t ; q ) ∞ ⁒ d q ⁒ t = ( 1 - q ) ⁒ ( q , - q , - 1 , - d ⁒ e , - d - 1 ⁒ e - 1 ⁒ q ; q ) ∞ ( d , - d , d - 1 ⁒ q , - d - 1 ⁒ q , e , - e , e - 1 ⁒ q , - e - 1 ⁒ q ; q ) ∞ superscript subscript 1 q-Pochhammer-symbol 𝑑 𝑑 𝑒 𝑑 π‘ž subscript 𝑑 π‘ž 𝑑 1 π‘ž q-Pochhammer-symbol π‘ž π‘ž 1 𝑑 𝑒 superscript 𝑑 1 1 π‘ž π‘ž q-Pochhammer-symbol 𝑑 𝑑 superscript 𝑑 1 π‘ž superscript 𝑑 1 π‘ž 𝑒 𝑒 1 π‘ž 1 π‘ž π‘ž {\displaystyle{\displaystyle{\displaystyle\int_{-\infty}^{\infty}\frac{1}{% \left(dt,et;q\right)_{\infty}}\,d_{q}t{}=(1-q)\,\frac{\left(q,-q,-1,-de,-d^{-1% }{\mathrm{e}^{-1}}q;q\right)_{\infty}}{\left(d,-d,d^{-1}q,-d^{-1}q,e,-e,{% \mathrm{e}^{-1}}q,-{\mathrm{e}^{-1}}q;q\right)_{\infty}}}}} {\displaystyle \int_{-\infty}^{\infty}\frac{1}{\qPochhammer{dt,et}{q}{\infty}}\,d_qt {}=(1-q)\,\frac{\qPochhammer{q,-q,-1,-de,-d^{-1}\expe^{-1}q}{q}{\infty}} {\qPochhammer{d,-d,d^{-1}q,-d^{-1}q,e,-e,\expe^{-1}q,-\expe^{-1}q}{q}{\infty}} }