Error(s) in re-building vignettes:
--- re-building ‘NAMI.Rnw’ using knitr
Error: processing vignette 'NAMI.Rnw' failed with diagnostics:
Running 'texi2dvi' on 'NAMI.tex' failed.
LaTeX errors:
! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Emergency stop.
 ...                                              
                                                  
l.161  \DeclareMathOperator{\Chi1}{\chi^2_1}
                                            
!  ==> Fatal error occurred, no output PDF file produced!
--- failed re-building ‘NAMI.Rnw’

--- re-building ‘mtram.Rnw’ using knitr
Error: processing vignette 'mtram.Rnw' failed with diagnostics:
Running 'texi2dvi' on 'mtram.tex' failed.
LaTeX errors:
! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Emergency stop.
 ...                                              
                                                  
l.232  \DeclareMathOperator{\Chi1}{\chi^2_1}
                                            
!  ==> Fatal error occurred, no output PDF file produced!
--- failed re-building ‘mtram.Rnw’

--- re-building ‘survtram.Rnw’ using knitr
Warning in doTryCatch(return(expr), name, parentenv, handler) :
  semi-transparency is not supported on this device: reported only once per page
Warning in doTryCatch(return(expr), name, parentenv, handler) :
  semi-transparency is not supported on this device: reported only once per page
Warning in doTryCatch(return(expr), name, parentenv, handler) :
  semi-transparency is not supported on this device: reported only once per page
Error: processing vignette 'survtram.Rnw' failed with diagnostics:
Running 'texi2dvi' on 'survtram.tex' failed.
LaTeX errors:
! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Emergency stop.
 ...                                              
                                                  
l.333  \DeclareMathOperator{\Chi1}{\chi^2_1}
                                            
!  ==> Fatal error occurred, no output PDF file produced!
--- failed re-building ‘survtram.Rnw’

--- re-building ‘tram.Rnw’ using knitr
Error: processing vignette 'tram.Rnw' failed with diagnostics:
Running 'texi2dvi' on 'tram.tex' failed.
LaTeX errors:
! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
! Emergency stop.
 ...                                              
                                                  
l.161  \DeclareMathOperator{\Chi1}{\chi^2_1}
                                            
!  ==> Fatal error occurred, no output PDF file produced!
--- failed re-building ‘tram.Rnw’

SUMMARY: processing the following files failed:
  ‘NAMI.Rnw’ ‘mtram.Rnw’ ‘survtram.Rnw’ ‘tram.Rnw’

Error: Vignette re-building failed.
Execution halted