anchor.diff:            END IF
           END DO
           a(i,i) = 1.d0 + a(i,i)     !Add identity matrix to a-matrix.
  -        b_(i1)  = y0(i)             !Initial abundances.
  +        bkevin(i1)  = y0(i)        !Initial abundances.
         END DO
   
   C50--------SOLVE EQUATIONS TO GET DERIVATIVE------------------------------------
  
positive.code:       COMMON /evolp2/ dt9,dhv,dphie,dydt             !Evolution parameters.
        COMMON /evolp3/ t90,hv0,phie0,y0               !Evolution parameters.
        COMMON /ttime/   t,dt,dlt9dt                   !Time varying parameters.
        COMMON /thermcb/  thm(14),hubcst                 !Dynamic variables.
        COMMON /endens/ rhone0,rhob0,rhob,rnb          !Energy densities.
        COMMON /lncoef/ a,b_,yx                         !Linear eqn coefficients.
        COMMON /flags/  ltime,is,ip,it,mbad            !Flags,counters.
        COMMON /runopt/ irun,isize,jsize               !Run option.
  
  
negative.code: 
  C----------COMMON AREAS.
        COMMON /compr/  cy,ct,t9i,t9f,ytmin,inc        !Computation parameters.
        COMMON /lncoef/ a,bkevin,y                     !Lin eqn coefficients. 
        COMMON /flags/  ltime,is,ip,it,mbad            !Flags, counters.
        COMMON /runopt/ irun,isize,jsize               !Run options.
  
  