epanech

double epanech(double x);

Returns the value of the Epanechnikov kernel at the point x.

Parameters:
xValue to evaluate the kernal at.

Returns:
If -1 ≤ x ≤ 1, 0.75 (1.0 - x2)
Otherwise, 0.0

Usage:
double r = epanech(0.75)

Header:
#include "kernels.h"