fjetrig.f

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C
C
C
        FUNCTION fjetrig(X,WGT)
        IMPLICIT REAL*8(a-h,o-z)
        REAL hipr1(100),hint1(100),ptmax,ptmin
        common/hiparnt/hipr1,ihpr2(50),hint1,ihnt2(50)
        SAVE  /hiparnt/
        dimension x(10)
        ptmin=abs(hipr1(10))-0.25
        ptmin=max(ptmin,hipr1(8))
        am2=0.d0
        IF(ihpr2(3).EQ.3) THEN
           am2=hipr1(7)**2
           ptmin=max(0.0,hipr1(10))
        ENDIF
        ptmax=abs(hipr1(10))+0.25
        IF(hipr1(10).LE.0.0) ptmax=hint1(1)/2.0-am2
        IF(ptmax.LE.ptmin) ptmax=ptmin+0.25
        pt2=(ptmax**2-ptmin**2)*x(1)+ptmin**2
        amt2=pt2+am2
        xt=2.0*dsqrt(amt2)/hint1(1)
        ymx1=dlog(1.0/xt+dsqrt(1.0/xt**2-1.0))
        y1=2.0*ymx1*x(2)-ymx1
        ymx2=dlog(2.0/xt-dexp(y1))
        ymn2=dlog(2.0/xt-dexp(-y1))
        y2=(ymx2+ymn2)*x(3)-ymn2
        IF(ihpr2(3).EQ.3) THEN
           gtrig=2.0*ghvq(y1,y2,amt2)
        ELSE IF(ihpr2(3).EQ.2) THEN
           gtrig=2.0*gphoton(y1,y2,pt2)
        ELSE
           gtrig=g(y1,y2,pt2)
        ENDIF
        fjetrig=2.0*ymx1*(ymx2+ymn2)*(ptmax**2-ptmin**2)
     &          *gtrig/2.0
        RETURN
        END