https://github.com/cran/quantreg
Tip revision: 470402e079549c584851dc1a2189d061adb01734 authored by Roger Koenker on 08 August 1977, 00:00:00 UTC
version 3.34
version 3.34
Tip revision: 470402e
akj.f
subroutine akj(x,z,p,iker,dens,psi,score,nx,nz,h,alpha,kappa,xlam)
double precision dens(nz),score(nz),psi(nz),h,kappa
double precision z(nz),x(nx),xlam(nx),p(nx),qrange,pi
double precision con1,sum,sqsum,xsd,a,fifth,hinv,half
double precision xn,xker,dxker,ddxker,fact,xponen,alpha,glog,zero,
& one,two
data zero/0.d0/
data one/1.d0/
data two/2.d0/
data four/4.d0/
data half/0.5d0/
data fifth/0.2d0/
data pi/3.141593d0/
xn=nx
if(.not.(iker.eq.0))goto 23000
con1=one/sqrt(2.0*pi)
goto 23001
23000 continue
if(.not.(iker.eq.1))goto 23002
con1=one/pi
23002 continue
23001 continue
if(.not.(h.le.0.))goto 23004
sum=0.
sqsum=0.
do 23006 i=1,nx
sqsum=sqsum+x(i)*x(i)*p(i)
sum=sum+x(i)*p(i)
23006 continue
xsd=dsqrt(sqsum-sum*sum)
sum=zero
i=1
23008 if(.not.(i.lt.nx))goto 23010
sum=sum+p(i)
if(.not.(sum.lt..25))goto 23011
goto 23009
23011 continue
qrange=x(i)
goto 23010
23012 continue
23009 i=i+1
goto 23008
23010 continue
sum=one
i=nx
23013 if(.not.(i.gt.0))goto 23015
sum=sum-p(i)
if(.not.(sum.gt..75))goto 23016
goto 23014
23016 continue
qrange=x(i)-qrange
goto 23015
23017 continue
23014 i=i-1
goto 23013
23015 continue
a=min(xsd,qrange/1.34)
h=kappa*a/(xn**fifth)
23004 continue
hinv=one/h
do 23018 j=1,nx
xker=0.
if(.not.(iker.eq.0))goto 23020
do 23022 i=1,nx
xponen=(x(j)-x(i))*hinv
xponen=half*xponen**2
xker=xker+p(i)*exp(-xponen)*hinv
23022 continue
goto 23021
23020 continue
if(.not.(iker.eq.1))goto 23024
do 23026 i=1,nx
xponen=(x(j)-x(i))*hinv
xker=xker+p(i)*hinv/(1+xponen**2)
23026 continue
23024 continue
23021 continue
xlam(j)=con1*xker
23018 continue
glog=zero
do 23028 i=1,nx
glog=glog+p(i)*log(xlam(i))
23028 continue
g=exp(glog)
ginv=one/g
do 23030 i=1,nx
xlam(i)=hinv/((xlam(i)*ginv)**(-alpha))
23030 continue
do 23032 j=1,nz
xker=zero
dxker=zero
ddxker=zero
if(.not.(iker.eq.0))goto 23034
do 23036 i=1,nx
xponen=(z(j)-x(i))*xlam(i)
fact=exp(-half*xponen*xponen)*xlam(i)
xker=xker+p(i)*fact
dxker=dxker-p(i)*fact*xponen*xlam(i)
ddxker=ddxker-p(i)*fact*(one - xponen**2)*xlam(i)**2
23036 continue
23034 continue
if(.not.(iker.eq.1))goto 23038
do 23040 i=1,nx
xponen=(z(j)-x(i))*xlam(i)
fact=xlam(i)/(one+xponen**2)
xker=xker+p(i)*fact
dxker=dxker-p(i)*two*xponen*fact**2
ddxker=ddxker-p(i)*two*(fact**2)*(xlam(i)-four*(xponen**2)*fact)
23040 continue
23038 continue
dens(j)=con1*xker
psi(j)=-(dxker/xker)
score(j)=(dxker/xker)**2-ddxker/xker
23032 continue
return
end