riwfun.F

Go to the documentation of this file. Or view the newest version in sPHENIX GitHub for file riwfun.F

C **********************************************************************

      DOUBLE PRECISION FUNCTION riwfun(V)
      
      IMPLICIT NONE
      
      DOUBLE PRECISION v(2)
      
*
* to avoid variable conflictions, a second keep element is necessary
* with the same common block name (see LPTOU2)
*
      COMMON /leptou/ cut(14),lst(40),parl(30),
     &                x,y,w2,q2,u
      REAL cut,parl,x,y,w2,q2,u
      INTEGER lst
      SAVE /leptou/

      COMMON /lintrl/ psave(3,4,5),ksave(4),xmin,xmax,ymin,ymax,
     &q2min,q2max,w2min,w2max,ilep,inu,ig,iz
      REAL psave,xmin,xmax,ymin,ymax,q2min,q2max,w2min,w2max
      INTEGER ksave,ilep,inu,ig,iz
      SAVE /lintrl/


      REAL v2min,v2max,v1min,v1max,v1,v2,dcross
      DATA v2min,v2max/2*0./

      riwfun=0.d0
      v1min=xmin
      v1max=xmax
      IF(lst(31).EQ.1) THEN
        v2min=q2min
        v2max=q2max
      ELSEIF(lst(31).EQ.2) THEN
        v2min=ymin
        v2max=ymax
      ELSEIF(lst(31).EQ.3) THEN
        v2min=w2min
        v2max=w2max
      ENDIF
      v1=v1min+v(1)*(v1max-v1min)
      v2=v2min+v(2)*(v2max-v2min)
      riwfun=dcross(v1,v2)*(v1max-v1min)*(v2max-v2min)

      RETURN
      END