SUBROUTINE S7(N,V,M,XX,YY,DEVN,IER,A)
      REAL X,Y,V(10),S(21),A(10,10), XX(20),YY(20),ABS,XI,DEVN
      DO 10 I=1,N
      V(I)=0.0
      S(I)=0.0
      NI=N+I-1
   10 S(NI)=0.
      IER=0
      K=2*N-1
      DO 20 J=1,M
      X=XX(J)
      Y=YY(J)
      XI=1.00
      DO 20 I=1,K
      IF(N.GE.I)V(I)=V(I)+XI *Y
      S(I)=S(I)+XI
   20 XI=XI*X
      DO 4 J=1,N
      K=N-J
      DO 4 I=1,N
      KI=K+I
    4 A(I,J)=S(KI)
      L=N-1
      DO 80 K=1,L
      K1=K+1
      I=K
      XI=ABS(A(K,K))
      DO 25 J=K1,N
      IF(XI.GE.ABS(A(J,K)))GO TO 25
      XI=ABS(A(J,K))
      I=J
   25 CONTINUE
      IF( I.EQ.K) GO TO 40
      DO 30 J=K,N
      XI=A(K,J)
      A(K,J)=A(I,J)
   30 A(I,J)=XI
      XI=V(K)
      V(K)=V(I)
      V(I)=XI
   40 IF  (A(K,K).NE.0.0) GO TO 50
      IER=1
      RETURN
C--------
   50 V(K)=V(K)/A(K,K)
      DO 60 I=K1,N
   60 V(I)=V(I)-A(I,K) *V(K)
      DO 80 J=K1,N
      A(K,J)=A(K,J)/A(K,K)
      DO 80 I=K1,N
   80 A(I,J)=A(I,J)-A(K,J)*A(I,K)
      V(N)=V(N)/A(N,N)
      DO 90 K=1,L
      I=N-K
      K1=I+1
      DO 90 J=K1,N
   90 V(I) =V(I)-A(I,J) *V(J)
      DEVN=0.0
      DO 110 I=1,M
      XI=V(1)
      DO 100 J=2,N
  100 XI=XI*XX(I)+V(J)
  110 DEVN=DEVN+(YY(I)-XI)**2
      RETURN
      END