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Bump function
Smooth and compactly supported function / From Wikipedia, the free encyclopedia
In mathematics, a bump function (also called a test function) is a function on a Euclidean space
which is both smooth (in the sense of having continuous derivatives of all orders) and compactly supported. The set of all bump functions with domain
forms a vector space, denoted
or
The dual space of this space endowed with a suitable topology is the space of distributions.
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