mnvert.f

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*
* $Id: mnvert.F,v 1.2 1996/03/15 18:02:54 james Exp $
*
* $Log: mnvert.F,v $
* Revision 1.2  1996/03/15 18:02:54  james
*     Modified Files:
* mnderi.F eliminate possible division by zero
* mnexcm.F suppress print on STOP when print flag=-1
*          set FVAL3 to flag if FCN already called with IFLAG=3
* mninit.F set version 96.03
* mnlims.F remove arguments, not needed
* mnmigr.F VLEN -> LENV in debug print statement
* mnparm.F move call to MNRSET to after NPAR redefined, to zero all
* mnpsdf.F eliminate possible division by zero
* mnscan.F suppress printout when print flag =-1
* mnset.F  remove arguments in call to MNLIMS
* mnsimp.F fix CSTATU so status is PROGRESS only if new minimum
* mnvert.F eliminate possible division by zero
*
* Revision 1.1.1.1  1996/03/07 14:31:32  mclareni
* Minuit
*
*
      SUBROUTINE mnvert(A,L,M,N,IFAIL)
*
* $Id: d506dp.inc,v 1.1.1.1 1996/03/07 14:31:32 mclareni Exp $
*
* $Log: d506dp.inc,v $
* Revision 1.1.1.1  1996/03/07 14:31:32  mclareni
* Minuit
*
*
*
*
* d506dp.inc
*
C ************ DOUBLE PRECISION VERSION *************
      IMPLICIT DOUBLE PRECISION (a-h,o-z)
CC        inverts a symmetric matrix.   matrix is first scaled to
CC        have all ones on the diagonal (equivalent to change of units)
CC        but no pivoting is done since matrix is positive-definite.
CC
*
* $Id: d506cm.inc,v 1.1.1.1 1996/03/07 14:31:32 mclareni Exp $
*
* $Log: d506cm.inc,v $
* Revision 1.1.1.1  1996/03/07 14:31:32  mclareni
* Minuit
*
*
*
*
* d506cm.inc
*
      parameter(mne=100 , mni=50)
      parameter(mnihl=mni*(mni+1)/2)
      CHARACTER*10 CPNAM
      COMMON
     1/mn7nam/ cpnam(mne)
     2/mn7ext/ u(mne)     ,alim(mne)  ,blim(mne)
     3/mn7err/ erp(mni)   ,ern(mni)   ,werr(mni)  ,globcc(mni)
     4/mn7inx/ nvarl(mne) ,niofex(mne),nexofi(mni)
     5/mn7int/ x(mni)     ,xt(mni)    ,dirin(mni)
     6/mn7fx2/ xs(mni)    ,xts(mni)   ,dirins(mni)
     7/mn7der/ grd(mni)   ,g2(mni)    ,gstep(mni) ,gin(mne) ,dgrd(mni)
     8/mn7fx3/ grds(mni)  ,g2s(mni)   ,gsteps(mni)
     9/mn7fx1/ ipfix(mni) ,npfix
     a/mn7var/ vhmat(mnihl)
     b/mn7vat/ vthmat(mnihl)
     c/mn7sim/ p(mni,mni+1),pstar(mni),pstst(mni) ,pbar(mni),prho(mni)
C
      parameter(maxdbg=10, maxstk=10, maxcwd=20, maxp=30, maxcpt=101)
      parameter(zero=0.0,  one=1.0,   half=0.5)
      COMMON
     d/mn7npr/ maxint ,npar   ,maxext ,nu
     e/mn7iou/ isysrd ,isyswr ,isyssa ,npagwd ,npagln ,newpag
     e/mn7io2/ istkrd(maxstk) ,nstkrd ,istkwr(maxstk) ,nstkwr
     f/mn7tit/ cfrom  ,cstatu ,ctitl  ,cword  ,cundef ,cvrsn ,covmes
     g/mn7flg/ isw(7) ,idbg(0:maxdbg) ,nblock ,icomnd
     h/mn7min/ amin   ,up     ,edm    ,fval3  ,epsi   ,apsi  ,dcovar
     i/mn7cnv/ nfcn   ,nfcnmx ,nfcnlc ,nfcnfr ,itaur,istrat,nwrmes(2)
     j/mn7arg/ word7(maxp)
     k/mn7log/ lwarn  ,lrepor ,limset ,lnolim ,lnewmn ,lphead
     l/mn7cns/ epsmac ,epsma2 ,vlimlo ,vlimhi ,undefi ,bigedm,updflt
     m/mn7rpt/ xpt(maxcpt)    ,ypt(maxcpt)
     n/mn7cpt/ chpt(maxcpt)
     o/mn7xcr/ xmidcr ,ymidcr ,xdircr ,ydircr ,ke1cr  ,ke2cr
      CHARACTER CTITL*50, CWORD*(maxcwd), CUNDEF*10, CFROM*8,
     +          cvrsn*6,  covmes(0:3)*22, cstatu*10, chpt*1
      LOGICAL   LWARN, LREPOR, LIMSET, LNOLIM, LNEWMN, LPHEAD
      dimension a(l,m) ,pp(mni), q(mni),  s(mni)
      ifail=0
      IF (n .LT. 1)  GO TO 100
      IF (n .GT. maxint)  GO TO 100
C                   scale matrix by sqrt of diag elements
      DO 8  i=1,n
      si = a(i,i)
      IF (si) 100,100,8
    8 s(i) = 1.0/sqrt(si)
      DO 20 i= 1, n
      DO 20 j= 1, n
   20 a(i,j) = a(i,j) *s(i)*s(j)
C                                        . . . start main loop . . . .
      DO 65 i=1,n
      k = i
C                   preparation for elimination step1
      IF (a(k,k) .EQ. zero)  GO TO 100
      q(k)=1./a(k,k)
      pp(k) = 1.0
      a(k,k)=0.0
      kp1=k+1
      km1=k-1
      IF(km1)100,50,40
   40 DO 49 j=1,km1
      pp(j)=a(j,k)
      q(j)=a(j,k)*q(k)
   49 a(j,k)=0.
   50 IF(k-n)51,60,100
   51 DO 59 j=kp1,n
      pp(j)=a(k,j)
      q(j)=-a(k,j)*q(k)
   59 a(k,j)=0.0
C                   elimination proper
   60 DO 65 j=1,n
      DO 65 k=j,n
   65 a(j,k)=a(j,k)+pp(j)*q(k)
C                   elements of left diagonal and unscaling
      DO 70 j= 1, n
      DO 70 k= 1, j
      a(k,j) = a(k,j) *s(k)*s(j)
   70 a(j,k) = a(k,j)
      RETURN
C                   failure return
  100 ifail=1
      RETURN
      END