|WikiProject Mathematics||(Rated Start-class, Low-priority)|
Please, can somebody create an image for this - I cannot understand this stub so far. 22.214.171.124 16:09, 24 June 2007 (UTC)
Drawing the diagram suggested just seems to make a regular parallel line to me. I have just come across the term antiparallel (in a physics text) used to describe a vector which is parallel to an axis but in the opposite sense. So perhaps antiparallel means something like this: if two vectors (or arrows or lines with direction) are parallel but in opposing senses then they are antiparallel. For example a left-to-right arrow is antiparallel to a right-to-left arrow. AP.
What are antiparallel vectors?
The article contains "In a vector space over R (or some other ordered field), two nonzero vectors are called antiparallel if they are parallel but have opposite directions." That defines nothing, as, in a vector space there is no notion of parallel vectors. The only notion is "colinear". When vectors are represented with arrows, they all start from the origin (the vector 0). The notion makes sense only for vectors with a starting point in an Euclidean space, but this kind of vector is more correctly called a "bi-point", and does not belong to any vector space. D.Lazard (talk) 23:52, 19 January 2014 (UTC)