anchor.diff:        return
         END
   
  +!----------------------------------------------------------------------C
  +
         FUNCTION ran2(idum)
         INTEGER idum,IM1,IM2,IMM1,IA1,IA2,IQ1,IQ2,IR1,IR2,NTAB,NDIV
         REAL ran2,AM,EPS,RNMX
  
positive.code:       ran2=min(AM*iy,RNMX)
        return
        END
  
        FUNCTION ran3(idum)
        INTEGER idum
  
negative.code:       IMPLICIT none
        REAL x1,x2,y1,y2,w,ran2
        INTEGER idum
    101 x1 = 2.0e0*ran2(idum) - 1.0e0
        x2 = 2.0e0*ran2(idum) - 1.0e0
        w  = x1*x1 + x2*x2
        if (w.ge.1.0e0) goto 101
  