svdfit.f

      SUBROUTINE SVDFIT(X,Y,SIG,NDATA,A,MA,U,V,W,MP,NP,CHISQ,FUNCS)
      PARAMETER(NMAX=1000,MMAX=50,TOL=1.E-5)
      DIMENSION X(NDATA),Y(NDATA),SIG(NDATA),A(MA),V(NP,NP),
     *    U(MP,NP),W(NP),B(NMAX),AFUNC(MMAX)
      DO 12 I=1,NDATA
        CALL FUNCS(X(I),AFUNC,MA)
        TMP=1./SIG(I)
        DO 11 J=1,MA
          U(I,J)=AFUNC(J)*TMP
11      CONTINUE
        B(I)=Y(I)*TMP
12    CONTINUE
      CALL SVDCMP(U,NDATA,MA,MP,NP,W,V)
      WMAX=0.
      DO 13 J=1,MA
        IF(W(J).GT.WMAX)WMAX=W(J)
13    CONTINUE
      THRESH=TOL*WMAX
      DO 14 J=1,MA
        IF(W(J).LT.THRESH)W(J)=0.
14    CONTINUE
      CALL SVBKSB(U,W,V,NDATA,MA,MP,NP,B,A)
      CHISQ=0.
      DO 16 I=1,NDATA
        CALL FUNCS(X(I),AFUNC,MA)
        SUM=0.
        DO 15 J=1,MA
          SUM=SUM+A(J)*AFUNC(J)
15      CONTINUE
        CHISQ=CHISQ+((Y(I)-SUM)/SIG(I))**2
16    CONTINUE
      RETURN
      END