Improper Rotation
The Symmetry Operation corresponding to a Rotation followed by an Inversion Operation, also called aRotoinversion. This operation is denoted 
for an improper rotation by 
, so the CrystallographyRestriction gives only 
, 
, 
, 
, 
for crystals. The Mirror Plane symmetryoperation is 
, etc., which is equivalent to .
- Medial Hexagonal Hexecontahedron
- Medial Icosacronic Hexecontahedron
- Medial Inverted Pentagonal Hexecontahedron
- Medial Pentagonal Hexecontahedron
- Medial Rhombic Triacontahedron
- Medial Triambic Icosahedron
- Medial Triangle
- Medial Triangle Locus Theorem
- Median Point
- Median (Statistics)
- Mediant
- Median (Triangle)
- Mega
- Megistron
- Mehler-Dirichlet Integral
- Mehler Quadrature
- Mehler's Bessel Function Formula
- Mehler's Hermite Polynomial Formula
- Meijer's G-Function
- Meissel's Formula
- Mellin Transform
- Melnikov-Arnold Integral
- Melodic Series
- MEM
- Memoryless