# Even function

From Encyclopedia of Mathematics

A function that does not change sign when the sign of the independent variable is changed, i.e. satisfying the condition $f(-x)=f(x)$. The graph of an even function is symmetric about the $y$-axis.

#### Comments

A function that does change sign when the sign of the independent variable is changed, i.e. satisfying the condition $f(x)=-f(-x)$, is called an odd function.

**How to Cite This Entry:**

Even function.

*Encyclopedia of Mathematics.*URL: http://encyclopediaofmath.org/index.php?title=Even_function&oldid=31495