The convert( expr, 'ModifiedMeijerG', x ) command converts the functions in x found in expr into their equivalent ModifiedMeijerG representation, whenever possible.  Most standard special and elementary functions can be so converted, along with many complex expressions involving these.

$\mathrm{convert}\left(\sin \left(z\right)\,'\mathrm{ModifiedMeijerG}'\,z\right)$

$\sqrt{\mathrm{\pi }}\mathrm{ModifiedMeijerG}\left(\left[\right]\,\left[\right]\,\left[\frac{1}{2}\right]\,\left[0\right]\,2\ln \left(z\right)-2\ln \left(2\right)\right)$

$\mathrm{convert}\left(\mathrm{BesselK}\left(3\,z\right)\exp \left(-az\right)\,'\mathrm{ModifiedMeijerG}'\,z\right)$

$\frac{\mathrm{ModifiedMeijerG}\left(\left[\right]\,\left[\right]\,\left[-\frac{3}{2}\,\frac{3}{2}\right]\,\left[\right]\,2\ln \left(z\right)-2\ln \left(2\right)\right)\mathrm{ModifiedMeijerG}\left(\left[\right]\,\left[\right]\,\left[0\right]\,\left[\right]\,\ln \left(z\right)+\ln \left(a\right)\right)}{2}$

$\mathrm{convert}\left(\mathrm{hypergeom}\left(\left[1\,2\right]\,\left[\frac{3}{2}\right]\,z\right)\,'\mathrm{ModifiedMeijerG}'\,z\right)$

$\frac{\sqrt{\mathrm{\pi }}\mathrm{ModifiedMeijerG}\left(\left[\mathrm{-1}\,0\right]\,\left[\right]\,\left[0\right]\,\left[-\frac{1}{2}\right]\,\ln \left(z\right)+\mathrm{I}\mathrm{\pi }\right)}{2}$

Prudnikov, A.P.; Brychkov, Yu; and Marichev, O. Integrals and Series. Gordon and Breach Science, 1990. Vol. 3: More Special Functions.

Roach, K. "Meijer G Function Representations." In Proceedings of ISSAC '97, pp. 205-211. Edited by Wolfgang Kuchlin. New York: ACM Press, 1997.