Science Fair Project Encyclopedia
Codomain
Given a function
, the set B is called the codomain of f.
The codomain is not to be confused with the range f(A), which is in general only a subset of B.
Example
Let the function f be a function on the real numbers:
defined by
The codomain of f is R, but clearly f(x) never takes negative values, and thus the range is in fact the set R+—non-negative reals, i.e. the interval [0,∞):
One could have defined the function g thus:
While f and g have the same effect on a given number, they are not, in the modern view, the same function since they have different codomains.
The codomain can affect whether or not the function is a surjection; in our example, g is a surjection while f is not.
See also
09-23-2007 01:00:40
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details


