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qlI3.f
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double complex function qlI3(p1,p2,p3,m1,m2,m3,mu2,ep)
implicit none
double precision p1,p2,p3,m1,m2,m3,mu2
integer ep
C pi=p(i)^2, i=1,2,3 are the four-momentum squared of the external lines
C mi=m(i)^2, i=1,2,3,are the squares of the masses of the internal lines
C mu2 is the square of the scale mu
C ep=-2,-1,0 chooses the coefficient in the Laurent series.
double precision psq(3),msq(3)
double precision p1o,p2o,p3o,m1o,m2o,m3o,mu2o,scalefac,newmu2
double complex Ival(-2:0)
integer epdum
logical qlzero
data p1o,p2o,p3o,m1o,m2o,m3o/6*0d0/
save Ival,p1o,p2o,p3o,m1o,m2o,m3o,mu2o
C--If we have already calculated, use the saved value
C--else setup the arrays
if ((p1 .eq. p1o)
. .and. (p2 .eq. p2o)
. .and. (p3 .eq. p3o)
. .and. (m1 .eq. m1o)
. .and. (m2 .eq. m2o)
. .and. (m3 .eq. m3o)
. .and. (mu2 .eq. mu2o)) then
qlI3=Ival(ep)
return
else
C---recalculate
p1o=p1
p2o=p2
p3o=p3
m1o=m1
m2o=m2
m3o=m3
mu2o=mu2
endif
scalefac=max(abs(m1),abs(m2),abs(m3),abs(p1),abs(p2),abs(p3))
msq(1)=m1/scalefac
msq(2)=m2/scalefac
msq(3)=m3/scalefac
psq(1)=p1/scalefac
psq(2)=p2/scalefac
psq(3)=p3/scalefac
newmu2=mu2/scalefac
C----sort msq in ascending order (and reorder psq correspondingly)
call qltrisort(psq,msq)
C----If internal masses all qlzero, reorder abs(psq) in ascending order
if (qlzero(abs(msq(1)))
. .and. qlzero(abs(msq(2)))
. .and. qlzero(abs(msq(3)))) then
call qlsnglsort(3,psq)
endif
C-----calculate value of integral
call qlI3sub(msq,psq,newmu2,Ival)
C---apply the rescaling to the integral
do epdum=-2,0
Ival(epdum)=Ival(epdum)/scalefac
enddo
qlI3=Ival(ep)
return
end

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