Integrand size = 10, antiderivative size = 162 \[ \int x^4 \text {erfi}(b x)^2 \, dx=-\frac {11 e^{2 b^2 x^2} x}{20 b^4 \pi }+\frac {e^{2 b^2 x^2} x^3}{5 b^2 \pi }-\frac {4 e^{b^2 x^2} \text {erfi}(b x)}{5 b^5 \sqrt {\pi }}+\frac {4 e^{b^2 x^2} x^2 \text {erfi}(b x)}{5 b^3 \sqrt {\pi }}-\frac {2 e^{b^2 x^2} x^4 \text {erfi}(b x)}{5 b \sqrt {\pi }}+\frac {1}{5} x^5 \text {erfi}(b x)^2+\frac {43 \text {erfi}\left (\sqrt {2} b x\right )}{40 b^5 \sqrt {2 \pi }} \]
-11/20*exp(2*b^2*x^2)*x/b^4/Pi+1/5*exp(2*b^2*x^2)*x^3/b^2/Pi+1/5*x^5*erfi( b*x)^2-4/5*exp(b^2*x^2)*erfi(b*x)/b^5/Pi^(1/2)+4/5*exp(b^2*x^2)*x^2*erfi(b *x)/b^3/Pi^(1/2)-2/5*exp(b^2*x^2)*x^4*erfi(b*x)/b/Pi^(1/2)+43/80*erfi(b*x* 2^(1/2))/b^5*2^(1/2)/Pi^(1/2)
Time = 0.03 (sec) , antiderivative size = 105, normalized size of antiderivative = 0.65 \[ \int x^4 \text {erfi}(b x)^2 \, dx=\frac {4 b e^{2 b^2 x^2} x \left (-11+4 b^2 x^2\right )-32 e^{b^2 x^2} \sqrt {\pi } \left (2-2 b^2 x^2+b^4 x^4\right ) \text {erfi}(b x)+16 b^5 \pi x^5 \text {erfi}(b x)^2+43 \sqrt {2 \pi } \text {erfi}\left (\sqrt {2} b x\right )}{80 b^5 \pi } \]
(4*b*E^(2*b^2*x^2)*x*(-11 + 4*b^2*x^2) - 32*E^(b^2*x^2)*Sqrt[Pi]*(2 - 2*b^ 2*x^2 + b^4*x^4)*Erfi[b*x] + 16*b^5*Pi*x^5*Erfi[b*x]^2 + 43*Sqrt[2*Pi]*Erf i[Sqrt[2]*b*x])/(80*b^5*Pi)
Time = 1.01 (sec) , antiderivative size = 260, normalized size of antiderivative = 1.60, number of steps used = 10, number of rules used = 10, \(\frac {\text {number of rules}}{\text {integrand size}}\) = 1.000, Rules used = {6920, 6941, 2641, 2641, 2633, 6941, 2641, 2633, 6938, 2633}
Below are the steps used by Rubi to obtain the solution. The rule number used for the transformation is given above next to the arrow. The rules definitions used are listed below.
\(\displaystyle \int x^4 \text {erfi}(b x)^2 \, dx\) |
\(\Big \downarrow \) 6920 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \int e^{b^2 x^2} x^5 \text {erfi}(b x)dx}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 6941 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (-\frac {2 \int e^{b^2 x^2} x^3 \text {erfi}(b x)dx}{b^2}-\frac {\int e^{2 b^2 x^2} x^4dx}{\sqrt {\pi } b}+\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}\right )}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 2641 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (-\frac {2 \int e^{b^2 x^2} x^3 \text {erfi}(b x)dx}{b^2}-\frac {\frac {x^3 e^{2 b^2 x^2}}{4 b^2}-\frac {3 \int e^{2 b^2 x^2} x^2dx}{4 b^2}}{\sqrt {\pi } b}+\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}\right )}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 2641 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (-\frac {2 \int e^{b^2 x^2} x^3 \text {erfi}(b x)dx}{b^2}-\frac {\frac {x^3 e^{2 b^2 x^2}}{4 b^2}-\frac {3 \left (\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\int e^{2 b^2 x^2}dx}{4 b^2}\right )}{4 b^2}}{\sqrt {\pi } b}+\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}\right )}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 2633 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (-\frac {2 \int e^{b^2 x^2} x^3 \text {erfi}(b x)dx}{b^2}+\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\frac {x^3 e^{2 b^2 x^2}}{4 b^2}-\frac {3 \left (\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}\right )}{4 b^2}}{\sqrt {\pi } b}\right )}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 6941 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (-\frac {2 \left (-\frac {\int e^{b^2 x^2} x \text {erfi}(b x)dx}{b^2}-\frac {\int e^{2 b^2 x^2} x^2dx}{\sqrt {\pi } b}+\frac {x^2 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}\right )}{b^2}+\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\frac {x^3 e^{2 b^2 x^2}}{4 b^2}-\frac {3 \left (\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}\right )}{4 b^2}}{\sqrt {\pi } b}\right )}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 2641 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (-\frac {2 \left (-\frac {\int e^{b^2 x^2} x \text {erfi}(b x)dx}{b^2}-\frac {\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\int e^{2 b^2 x^2}dx}{4 b^2}}{\sqrt {\pi } b}+\frac {x^2 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}\right )}{b^2}+\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\frac {x^3 e^{2 b^2 x^2}}{4 b^2}-\frac {3 \left (\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}\right )}{4 b^2}}{\sqrt {\pi } b}\right )}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 2633 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (-\frac {2 \left (-\frac {\int e^{b^2 x^2} x \text {erfi}(b x)dx}{b^2}+\frac {x^2 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}}{\sqrt {\pi } b}\right )}{b^2}+\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\frac {x^3 e^{2 b^2 x^2}}{4 b^2}-\frac {3 \left (\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}\right )}{4 b^2}}{\sqrt {\pi } b}\right )}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 6938 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (-\frac {2 \left (-\frac {\frac {e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\int e^{2 b^2 x^2}dx}{\sqrt {\pi } b}}{b^2}+\frac {x^2 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}}{\sqrt {\pi } b}\right )}{b^2}+\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\frac {x^3 e^{2 b^2 x^2}}{4 b^2}-\frac {3 \left (\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}\right )}{4 b^2}}{\sqrt {\pi } b}\right )}{5 \sqrt {\pi }}\) |
\(\Big \downarrow \) 2633 |
\(\displaystyle \frac {1}{5} x^5 \text {erfi}(b x)^2-\frac {4 b \left (\frac {x^4 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {2 \left (\frac {x^2 e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\frac {e^{b^2 x^2} \text {erfi}(b x)}{2 b^2}-\frac {\text {erfi}\left (\sqrt {2} b x\right )}{2 \sqrt {2} b^2}}{b^2}-\frac {\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}}{\sqrt {\pi } b}\right )}{b^2}-\frac {\frac {x^3 e^{2 b^2 x^2}}{4 b^2}-\frac {3 \left (\frac {x e^{2 b^2 x^2}}{4 b^2}-\frac {\sqrt {\frac {\pi }{2}} \text {erfi}\left (\sqrt {2} b x\right )}{8 b^3}\right )}{4 b^2}}{\sqrt {\pi } b}\right )}{5 \sqrt {\pi }}\) |
(x^5*Erfi[b*x]^2)/5 - (4*b*((E^(b^2*x^2)*x^4*Erfi[b*x])/(2*b^2) - ((E^(2*b ^2*x^2)*x^3)/(4*b^2) - (3*((E^(2*b^2*x^2)*x)/(4*b^2) - (Sqrt[Pi/2]*Erfi[Sq rt[2]*b*x])/(8*b^3)))/(4*b^2))/(b*Sqrt[Pi]) - (2*((E^(b^2*x^2)*x^2*Erfi[b* x])/(2*b^2) - ((E^(b^2*x^2)*Erfi[b*x])/(2*b^2) - Erfi[Sqrt[2]*b*x]/(2*Sqrt [2]*b^2))/b^2 - ((E^(2*b^2*x^2)*x)/(4*b^2) - (Sqrt[Pi/2]*Erfi[Sqrt[2]*b*x] )/(8*b^3))/(b*Sqrt[Pi])))/b^2))/(5*Sqrt[Pi])
3.3.35.3.1 Defintions of rubi rules used
Int[(F_)^((a_.) + (b_.)*((c_.) + (d_.)*(x_))^2), x_Symbol] :> Simp[F^a*Sqrt [Pi]*(Erfi[(c + d*x)*Rt[b*Log[F], 2]]/(2*d*Rt[b*Log[F], 2])), x] /; FreeQ[{ F, a, b, c, d}, x] && PosQ[b]
Int[(F_)^((a_.) + (b_.)*((c_.) + (d_.)*(x_))^(n_))*((c_.) + (d_.)*(x_))^(m_ .), x_Symbol] :> Simp[(c + d*x)^(m - n + 1)*(F^(a + b*(c + d*x)^n)/(b*d*n*L og[F])), x] - Simp[(m - n + 1)/(b*n*Log[F]) Int[(c + d*x)^(m - n)*F^(a + b*(c + d*x)^n), x], x] /; FreeQ[{F, a, b, c, d}, x] && IntegerQ[2*((m + 1)/ n)] && LtQ[0, (m + 1)/n, 5] && IntegerQ[n] && (LtQ[0, n, m + 1] || LtQ[m, n , 0])
Int[Erfi[(b_.)*(x_)]^2*(x_)^(m_.), x_Symbol] :> Simp[x^(m + 1)*(Erfi[b*x]^2 /(m + 1)), x] - Simp[4*(b/(Sqrt[Pi]*(m + 1))) Int[x^(m + 1)*E^(b^2*x^2)*E rfi[b*x], x], x] /; FreeQ[b, x] && (IGtQ[m, 0] || ILtQ[(m + 1)/2, 0])
Int[E^((c_.) + (d_.)*(x_)^2)*Erfi[(a_.) + (b_.)*(x_)]*(x_), x_Symbol] :> Si mp[E^(c + d*x^2)*(Erfi[a + b*x]/(2*d)), x] - Simp[b/(d*Sqrt[Pi]) Int[E^(a ^2 + c + 2*a*b*x + (b^2 + d)*x^2), x], x] /; FreeQ[{a, b, c, d}, x]
Int[E^((c_.) + (d_.)*(x_)^2)*Erfi[(a_.) + (b_.)*(x_)]*(x_)^(m_), x_Symbol] :> Simp[x^(m - 1)*E^(c + d*x^2)*(Erfi[a + b*x]/(2*d)), x] + (-Simp[(m - 1)/ (2*d) Int[x^(m - 2)*E^(c + d*x^2)*Erfi[a + b*x], x], x] - Simp[b/(d*Sqrt[ Pi]) Int[x^(m - 1)*E^(a^2 + c + 2*a*b*x + (b^2 + d)*x^2), x], x]) /; Free Q[{a, b, c, d}, x] && IGtQ[m, 1]
\[\int x^{4} \operatorname {erfi}\left (b x \right )^{2}d x\]
Time = 0.26 (sec) , antiderivative size = 114, normalized size of antiderivative = 0.70 \[ \int x^4 \text {erfi}(b x)^2 \, dx=\frac {16 \, \pi b^{6} x^{5} \operatorname {erfi}\left (b x\right )^{2} - 32 \, \sqrt {\pi } {\left (b^{5} x^{4} - 2 \, b^{3} x^{2} + 2 \, b\right )} \operatorname {erfi}\left (b x\right ) e^{\left (b^{2} x^{2}\right )} - 43 \, \sqrt {2} \sqrt {\pi } \sqrt {-b^{2}} \operatorname {erf}\left (\sqrt {2} \sqrt {-b^{2}} x\right ) + 4 \, {\left (4 \, b^{4} x^{3} - 11 \, b^{2} x\right )} e^{\left (2 \, b^{2} x^{2}\right )}}{80 \, \pi b^{6}} \]
1/80*(16*pi*b^6*x^5*erfi(b*x)^2 - 32*sqrt(pi)*(b^5*x^4 - 2*b^3*x^2 + 2*b)* erfi(b*x)*e^(b^2*x^2) - 43*sqrt(2)*sqrt(pi)*sqrt(-b^2)*erf(sqrt(2)*sqrt(-b ^2)*x) + 4*(4*b^4*x^3 - 11*b^2*x)*e^(2*b^2*x^2))/(pi*b^6)
\[ \int x^4 \text {erfi}(b x)^2 \, dx=\int x^{4} \operatorname {erfi}^{2}{\left (b x \right )}\, dx \]
\[ \int x^4 \text {erfi}(b x)^2 \, dx=\int { x^{4} \operatorname {erfi}\left (b x\right )^{2} \,d x } \]
\[ \int x^4 \text {erfi}(b x)^2 \, dx=\int { x^{4} \operatorname {erfi}\left (b x\right )^{2} \,d x } \]
Timed out. \[ \int x^4 \text {erfi}(b x)^2 \, dx=\int x^4\,{\mathrm {erfi}\left (b\,x\right )}^2 \,d x \]