SUBROUTINE LEVSOL(A,B,POPP,NLVCAL)
C     ==================================
C
      INCLUDE 'PARAMS.FOR'
      INCLUDE 'MODELP.FOR'
      DIMENSION A(MLEVEL,MLEVEL),B(MLEVEL),POPP(MLEVEL),
     *          AP(MLEVEL,MLEVEL),BP(MLEVEL),POPP1(MLEVEL)
C
C     new populations by inverting several partial rate matrices for the
C     individual chemical species
C
      if(nlvcal.le.0) return
         DO 50 IAT=1,NATOM
            N1=N0A(IAT)
            NK=NKA(IAT)
            IF(N1.LE.0) THEN
               DO 1 I=N0A(IAT),NKA(IAT)
                  N1=I
                  IF(I.GT.0) GO TO 2
    1          CONTINUE
    2          CONTINUE
            END IF
            IF(N1.LE.0) GO TO 50
            NLP=NK-N1+1
            DO 20 I=N1,NK
               DO 10 J=N1,NK
                  AP(I-N1+1,J-N1+1)=A(I,J)
   10          CONTINUE
               BP(I-N1+1)=B(I)
   20       CONTINUE
            CALL LINEQS(AP,BP,POPP1,NLP,MLEVEL)
            DO 30 I=N1,NK
                POPP(I)=POPP1(I-N1+1)
   30       CONTINUE
   50    CONTINUE
      RETURN
      END