anchor.diff:  
   C----------MATRIX COEFFICIENTS FOR LINEAR EQUATION.
         DOUBLE PRECISION a(nnuc,nnuc)!Coefficient array.
  -      REAL    b_(nnuc)              !Right-hand vector w/o manipulation.
  +      REAL    bkevin(nnuc)         !Right-hand vector w/o manipulation.
         REAL    y(nnuc)              !Solution vector.
   
   C----------COUNTERS AND FLAGS.
  
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:       mbad = 0                     !No errors yet.
  C..........SET RIGHT-HAND AND SOLUTION VECTORS TO INITIAL VALUES.
        DO i = 1,isize
          x(i) = bkevin(i)           !Right-hand vector.
          y(i) = 0.                  !Solution vector.
        END DO
  C..........SAVE MATRIX.
  