*-- Author : S.Burke
      DOUBLE PRECISION FUNCTION FKCHXY(XY,CXY,SVEC,CVEC,IERR)
*-----------------------------------------Updates 27/07/93-------                                             
**: FKCHXY 30907 SB. Function now (correctly) double precision.                                               
**********************************************************************                                        
*                                                                    *                                        
* Calculate (filtered/smoothed) chi-squared for an x-y measurement   *                                        
*                                                                    *                                        
* ERROR CONDITIONS;                                                  *                                        
*       IERR =   0 ; normal termination                              *                                        
*   ->  IERR = 112 ; CRES not positive definite                      *                                        
*                                                                    *                                        
*   ->  Fatal error                                                  *                                        
*                                                                    *                                        
**********************************************************************                                        
*KEEP,FKECODE.                                                                                                
*KEND.                                                                                                        
**********************************************************************                                        
* Calculate the residuals and covariance ...                                                                  
* ... and the chi-squared                                                                                     
         CALL FKERR(IUTIL,IROUT,IFATAL,IRCV,IERR)
*