R help - Apr 2007 - bquote in plot.default vs plot.formula ?

Folks:

If it's not too technical, could someone explain the following:

x <- 1:5; y <- x

## The following 3 all work as expected:

plot(x,y, main= expression(sin(x+1)))
plot(y~x, main= expression(sin(x+2 )))
plot(x,y, main= bquote(sin(x+3)))

## The following does not:
plot(y~x, main= bquote(sin(x+4)))

## Perhaps more interesting results occur if "log[10]" is substituted
for
"sin" in these expressions. The last plot command then produces the
error
message: "Error in log[10] : object is not subsettable"

Feel free to reply offline if you think that's more appropriate. Version
info below.

Cheers,
Bert

Bert Gunter
Genentech Nonclinical Statistics
South San Francisco, CA 94404
650-467-7374


Version info:

 R.Version()
$platform
[1] "i386-pc-mingw32"

$arch
[1] "i386"

$os
[1] "mingw32"

$system
[1] "i386, mingw32"

$status
[1] ""

$major
[1] "2"

$minor
[1] "4.1"

$year
[1] "2006"

$month
[1] "12"

$day
[1] "18"

$`svn rev`
[1] "40228"

$language
[1] "R"

$version.string
[1] "R version 2.4.1 (2006-12-18)"