path of the output file for knit(); if NULL, this
function will try to guess and it will be under the current working
directory
compiler
a character string which gives the LaTeX program used to
compile the tex document to PDF (by default it uses the default setting of
texi2pdf, which is often PDFLaTeX); this argument will
be used to temporarily set the environmental variable PDFLATEX. For
an Rrst file, setting compiler to 'rst2pdf' will use
rst2pdf to compiles the rst file to PDF using the ReportLab
open-source library.
envir
the environment in which the code chunks are to be evaluated
(for example, parent.frame(), new.env(), or
globalenv())