ISCE_INSAR/components/isceobj/Util/src/lfit.F

91 lines
1.7 KiB
Fortran

SUBROUTINE LFIT(X,Y,SIG,NDATA,A,MA,LISTA,MFIT,COVAR,NCVM,CHISQ)
PARAMETER (MMAX=50)
implicit real*8 (a-h,o-z)
real*8 x(*)
real*8 sig(*),y(*)
DIMENSION A(MA),LISTA(MA),
* COVAR(NCVM,NCVM),BETA(MMAX),AFUNC(MMAX)
KK=MFIT+1
DO 12 J=1,MA
IHIT=0
DO 11 K=1,MFIT
IF (LISTA(K).EQ.J) IHIT=IHIT+1
11 CONTINUE
IF (IHIT.EQ.0) THEN
LISTA(KK)=J
KK=KK+1
ELSE IF (IHIT.GT.1) THEN
PAUSE 'Improper set in LISTA'
ENDIF
12 CONTINUE
IF (KK.NE.(MA+1)) PAUSE 'Improper set in LISTA'
DO 14 J=1,MFIT
DO 13 K=1,MFIT
COVAR(J,K)=0.
13 CONTINUE
BETA(J)=0.
14 CONTINUE
DO 18 I=1,NDATA
CALL FUNCS(X(I),AFUNC,MA)
YM=Y(I)
IF(MFIT.LT.MA) THEN
DO 15 J=MFIT+1,MA
YM=YM-A(LISTA(J))*AFUNC(LISTA(J))
15 CONTINUE
ENDIF
SIG2I=1./SIG(I)**2
DO 17 J=1,MFIT
WT=AFUNC(LISTA(J))*SIG2I
DO 16 K=1,J
COVAR(J,K)=COVAR(J,K)+WT*AFUNC(LISTA(K))
16 CONTINUE
BETA(J)=BETA(J)+YM*WT
17 CONTINUE
18 CONTINUE
IF (MFIT.GT.1) THEN
DO 21 J=2,MFIT
DO 19 K=1,J-1
COVAR(K,J)=COVAR(J,K)
19 CONTINUE
21 CONTINUE
ENDIF
CALL GAUSSJ(COVAR,MFIT,NCVM,BETA,1,1)
DO 22 J=1,MFIT
A(LISTA(J))=BETA(J)
22 CONTINUE
CHISQ=0.
DO 24 I=1,NDATA
CALL FUNCS(X(I),AFUNC,MA)
SUM=0.
DO 23 J=1,MA
SUM=SUM+A(J)*AFUNC(J)
23 CONTINUE
CHISQ=CHISQ+((Y(I)-SUM)/SIG(I))**2
24 CONTINUE
c CALL COVSRT(COVAR,NCVM,MA,LISTA,MFIT)
RETURN
END