Integrand size = 10, antiderivative size = 113 \[ \int x^2 \text {erf}(b x)^2 \, dx=\frac {e^{-2 b^2 x^2} x}{3 b^2 \pi }+\frac {2 e^{-b^2 x^2} \text {erf}(b x)}{3 b^3 \sqrt {\pi }}+\frac {2 e^{-b^2 x^2} x^2 \text {erf}(b x)}{3 b \sqrt {\pi }}+\frac {1}{3} x^3 \text {erf}(b x)^2-\frac {5 \text {erf}\left (\sqrt {2} b x\right )}{6 b^3 \sqrt {2 \pi }} \]
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Time = 0.10 (sec) , antiderivative size = 113, normalized size of antiderivative = 1.00, number of steps used = 6, number of rules used = 5, \(\frac {\text {number of rules}}{\text {integrand size}}\) = 0.500, Rules used = {6499, 6520, 6517, 2236, 2243} \[ \int x^2 \text {erf}(b x)^2 \, dx=-\frac {5 \text {erf}\left (\sqrt {2} b x\right )}{6 \sqrt {2 \pi } b^3}+\frac {2 x^2 e^{-b^2 x^2} \text {erf}(b x)}{3 \sqrt {\pi } b}+\frac {x e^{-2 b^2 x^2}}{3 \pi b^2}+\frac {2 e^{-b^2 x^2} \text {erf}(b x)}{3 \sqrt {\pi } b^3}+\frac {1}{3} x^3 \text {erf}(b x)^2 \]
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Rule 2236
Rule 2243
Rule 6499
Rule 6517
Rule 6520
Rubi steps \begin{align*} \text {integral}& = \frac {1}{3} x^3 \text {erf}(b x)^2-\frac {(4 b) \int e^{-b^2 x^2} x^3 \text {erf}(b x) \, dx}{3 \sqrt {\pi }} \\ & = \frac {2 e^{-b^2 x^2} x^2 \text {erf}(b x)}{3 b \sqrt {\pi }}+\frac {1}{3} x^3 \text {erf}(b x)^2-\frac {4 \int e^{-2 b^2 x^2} x^2 \, dx}{3 \pi }-\frac {4 \int e^{-b^2 x^2} x \text {erf}(b x) \, dx}{3 b \sqrt {\pi }} \\ & = \frac {e^{-2 b^2 x^2} x}{3 b^2 \pi }+\frac {2 e^{-b^2 x^2} \text {erf}(b x)}{3 b^3 \sqrt {\pi }}+\frac {2 e^{-b^2 x^2} x^2 \text {erf}(b x)}{3 b \sqrt {\pi }}+\frac {1}{3} x^3 \text {erf}(b x)^2-\frac {\int e^{-2 b^2 x^2} \, dx}{3 b^2 \pi }-\frac {4 \int e^{-2 b^2 x^2} \, dx}{3 b^2 \pi } \\ & = \frac {e^{-2 b^2 x^2} x}{3 b^2 \pi }+\frac {2 e^{-b^2 x^2} \text {erf}(b x)}{3 b^3 \sqrt {\pi }}+\frac {2 e^{-b^2 x^2} x^2 \text {erf}(b x)}{3 b \sqrt {\pi }}+\frac {1}{3} x^3 \text {erf}(b x)^2-\frac {\sqrt {\frac {2}{\pi }} \text {erf}\left (\sqrt {2} b x\right )}{3 b^3}-\frac {\text {erf}\left (\sqrt {2} b x\right )}{6 b^3 \sqrt {2 \pi }} \\ \end{align*}
Time = 0.05 (sec) , antiderivative size = 88, normalized size of antiderivative = 0.78 \[ \int x^2 \text {erf}(b x)^2 \, dx=\frac {4 b e^{-2 b^2 x^2} x+8 e^{-b^2 x^2} \sqrt {\pi } \left (1+b^2 x^2\right ) \text {erf}(b x)+4 b^3 \pi x^3 \text {erf}(b x)^2-5 \sqrt {2 \pi } \text {erf}\left (\sqrt {2} b x\right )}{12 b^3 \pi } \]
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Time = 0.54 (sec) , antiderivative size = 95, normalized size of antiderivative = 0.84
method | result | size |
derivativedivides | \(\frac {\frac {\operatorname {erf}\left (b x \right )^{2} b^{3} x^{3}}{3}-\frac {4 \,\operatorname {erf}\left (b x \right ) \left (-\frac {x^{2} {\mathrm e}^{-b^{2} x^{2}} b^{2}}{2}-\frac {{\mathrm e}^{-b^{2} x^{2}}}{2}\right )}{3 \sqrt {\pi }}+\frac {-\frac {5 \sqrt {2}\, \sqrt {\pi }\, \operatorname {erf}\left (b x \sqrt {2}\right )}{12}+\frac {{\mathrm e}^{-2 b^{2} x^{2}} b x}{3}}{\pi }}{b^{3}}\) | \(95\) |
default | \(\frac {\frac {\operatorname {erf}\left (b x \right )^{2} b^{3} x^{3}}{3}-\frac {4 \,\operatorname {erf}\left (b x \right ) \left (-\frac {x^{2} {\mathrm e}^{-b^{2} x^{2}} b^{2}}{2}-\frac {{\mathrm e}^{-b^{2} x^{2}}}{2}\right )}{3 \sqrt {\pi }}+\frac {-\frac {5 \sqrt {2}\, \sqrt {\pi }\, \operatorname {erf}\left (b x \sqrt {2}\right )}{12}+\frac {{\mathrm e}^{-2 b^{2} x^{2}} b x}{3}}{\pi }}{b^{3}}\) | \(95\) |
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Time = 0.26 (sec) , antiderivative size = 90, normalized size of antiderivative = 0.80 \[ \int x^2 \text {erf}(b x)^2 \, dx=\frac {4 \, \pi b^{4} x^{3} \operatorname {erf}\left (b x\right )^{2} + 4 \, b^{2} x e^{\left (-2 \, b^{2} x^{2}\right )} + 8 \, \sqrt {\pi } {\left (b^{3} x^{2} + b\right )} \operatorname {erf}\left (b x\right ) e^{\left (-b^{2} x^{2}\right )} - 5 \, \sqrt {2} \sqrt {\pi } \sqrt {b^{2}} \operatorname {erf}\left (\sqrt {2} \sqrt {b^{2}} x\right )}{12 \, \pi b^{4}} \]
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\[ \int x^2 \text {erf}(b x)^2 \, dx=\int x^{2} \operatorname {erf}^{2}{\left (b x \right )}\, dx \]
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\[ \int x^2 \text {erf}(b x)^2 \, dx=\int { x^{2} \operatorname {erf}\left (b x\right )^{2} \,d x } \]
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Time = 0.28 (sec) , antiderivative size = 111, normalized size of antiderivative = 0.98 \[ \int x^2 \text {erf}(b x)^2 \, dx=\frac {1}{3} \, x^{3} \operatorname {erf}\left (b x\right )^{2} + \frac {b {\left (\frac {8 \, {\left (b^{2} x^{2} + 1\right )} \operatorname {erf}\left (b x\right ) e^{\left (-b^{2} x^{2}\right )}}{b^{4}} + \frac {b^{2} {\left (\frac {4 \, x e^{\left (-2 \, b^{2} x^{2}\right )}}{b^{2}} + \frac {\sqrt {2} \sqrt {\pi } \operatorname {erf}\left (-\sqrt {2} b x\right )}{b^{3}}\right )} + \frac {4 \, \sqrt {2} \sqrt {\pi } \operatorname {erf}\left (-\sqrt {2} b x\right )}{b}}{\sqrt {\pi } b^{3}}\right )}}{12 \, \sqrt {\pi }} \]
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Time = 0.19 (sec) , antiderivative size = 90, normalized size of antiderivative = 0.80 \[ \int x^2 \text {erf}(b x)^2 \, dx=\frac {x^3\,{\mathrm {erf}\left (b\,x\right )}^2}{3}+\frac {\frac {2\,\sqrt {\pi }\,{\mathrm {e}}^{-b^2\,x^2}\,\mathrm {erf}\left (b\,x\right )}{3}-\frac {5\,\sqrt {2}\,\sqrt {\pi }\,\mathrm {erf}\left (\sqrt {2}\,b\,x\right )}{12}+\frac {b\,x\,{\mathrm {e}}^{-2\,b^2\,x^2}}{3}+\frac {2\,b^2\,x^2\,\sqrt {\pi }\,{\mathrm {e}}^{-b^2\,x^2}\,\mathrm {erf}\left (b\,x\right )}{3}}{b^3\,\pi } \]
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