Editing Dual number (section)

==History==
Dual numbers were introduced in 1873 by [[William Kingdon Clifford|William Clifford]], and were used at the beginning of the twentieth century by the German mathematician [[Eduard Study]], who used them to represent the dual angle which measures the relative position of two [[skew lines]] in space. Study defined a dual angle as {{math|''θ'' + ''dε''}}, where {{mvar|θ}} is the angle between the directions of two lines in three-dimensional space and {{mvar|d}} is a distance between them. The {{mvar|n}}-dimensional generalization, the [[Grassmann number]], was introduced by [[Hermann Grassmann]] in the late 19th century.