This file contains code chunks with logical and numerical options that
take their value from variables defined in previous chunks.

<<a>>=
doit <- TRUE
@

<<b, eval=doit>>=
wd <- 4
ht <- 5
@

<<c, fig=TRUE, width=wd, height=ht>>=
plot(1)
@

The following chunk verifies that unknown options can use any value
without error.
<<foo=bar>>=
x <- 42
@