sorry I know this might involve expression and paste but I've spent ages not getting this right I need sigma^2=a variable value as a title in R you can see these efforts don't work
val<-2
plot(1:10,main=paste(expression("sigma^2"),"=",val))
plot(1:10,main=expression(paste("sigma^2"),"=",val))
many thanks for any advie from wise gurus