Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

 Library: kernel See also: cosi epa gau tri trian uni qua rqua

 Quantlet: bqua2 Description: computes the second derivative of the quartic kernel with boundary correction

 Usage: y = bqua2(x,rho) Input: x n x 1 vector, the data at which the kernel is to be computed; zero outside (-1, rho) rho scalar or n x 1 vector containing the distance to the boundary relative to bandwidth; 0<=rho<=1 Output: y n x 1 vector containing the values of the kernel at given points

Example:
```library("kernel")
x = aseq(-1, 50, 0.04)
y = bqua2(x,0.5)
t = createdisplay(1,1)
show(t,1,1,x~y)

```
Result:
```The kernel is pictured.
```
Example:
```library("kernel")
library("plot")
n = 200
x =(1:(n))/(n)
x=(-x[(n):1])|0|x
y=bqua2(x,1)
y9=bqua2(x,0.9)
y8=bqua2(x,0.8)
y7=bqua2(x,0.7)
y6=bqua2(x,0.6)
y5=bqua2(x,0.5)
y4=bqua2(x,0.4)
y3=bqua2(x,0.3)
y2=bqua2(x,0.2)
y1=bqua2(x,0.1)
y0=bqua2(x,0)
axes=graxes(#(-1.2,1.2)~#(min(y0),max(y0)),"origin",0|0,"xticks",#(-1,-0.5,0.5,1),"yticks",#(min(y0)|max(y0)))
axesoff()
setsize(600,300)
di2 = createdisplay(1, 1)
show(di2, 1, 1, xy, xy9, xy8, xy7, xy6, xy5, xy4, xy3, xy2, xy1, xy0, axes)

```
Result:
```Sequence of kernel derivatives with rho varying from 0 to 1 is pictured.
```

Author: Z. Hlavka, 20030123 license MD*Tech
(C) MD*TECH Method and Data Technologies, 05.02.2006