--- DarthVader/TrackerLevel2/src/F77/mini.f	2006/11/08 16:42:28	1.5
+++ DarthVader/TrackerLevel2/src/F77/mini.f	2006/11/14 16:21:09	1.6
@@ -41,8 +41,8 @@
 *                               !the tracking procedure
       DATA STEPMAX/100./        !maximum number of steps in the trackin gprocess
 
-      DATA ALMAX/dinf,dinf,1.,dinf,dinf/ !limits on alpha vector components
-      DATA ALMIN/-dinf,-dinf,-1.,-dinf,-dinf/ !"
+      DATA ALMAX/dinf,dinf,dinf,dinf,dinf/ !limits on alpha vector components
+      DATA ALMIN/-dinf,-dinf,-dinf,-dinf,-dinf/ !"
 
       DIMENSION DAL(5)                    !increment of vector alfa
       DIMENSION CHI2DD_R(4,4),CHI2D_R(4) !hessiano e gradiente di chi2
@@ -138,7 +138,18 @@
          RETURN
       ENDIF
       
-      COST=1e-7
+      COST=1e-9
+      costfac=1.1
+      flagstep=0
+
+ 7    continue
+
+       IF(costfac.le.1.) THEN
+        IFAIL=1
+        PRINT *,'=== WARNING ===> no matrix inversion '
+        RETURN
+       ENDIF
+
       DO I=1,5
          DO J=1,5
             CHI2DD(I,J)=CHI2DD(I,J)*COST
@@ -152,17 +163,30 @@
 *     track fitting with FREE deflection
 *------------------------------------------------------------*
          CALL DSFACT(5,CHI2DD,5,IFA,DET,JFA) !CHI2DD matrix determinant
-         IF(IFA.NE.0) THEN      !not positive-defined      
-            if(TRKVERBOSE)then
+         IF(IFA.NE.0.or.jfa.ne.0) THEN      !not positive-defined      
+           if(ifa.eq.-1)then
+             if(TRKVERBOSE)then
                PRINT *,
      $              '*** ERROR in mini ***'//
      $              'on matrix inversion (not pos-def)'
      $              ,DET
-            endif
-            IF(CHI2.EQ.0) CHI2=-9999.
-            IF(CHI2.GT.0) CHI2=-CHI2
-            IFAIL=1
-            RETURN             
+             endif
+             IF(CHI2.EQ.0) CHI2=-9999.
+             IF(CHI2.GT.0) CHI2=-CHI2
+             IFAIL=1
+             RETURN  
+           endif
+           if(jfa.eq.-1)then
+             if(flagstep.eq.-1.) costfac=(costfac-1)/2+1
+             cost=cost*costfact
+             flagstep=1.
+             goto 7
+           elseif(jfa.eq.1)then
+             if(flagstep.eq.1.) costfac=(costfac-1)/2+1
+             cost=cost/costfac
+             flagstep=-1.
+             goto 7
+           endif
          ENDIF
          CALL DSFINV(5,CHI2DD,5) !CHI2DD matrix inversion    
 *     *******************************************