R help - Mar 2010 - How the change the dimension of an individual cell [i.e. the cell corresponding to an observation in data matrix] in a heatmap.2?

Dear R-Helpers,
I have a short question related to heatmap.2 function. I wanted to change
the dimension of each cell in the heatmap drawn by this function.

here is a reproducible example from the help page

library(gplots)
data(mtcars)
x  <- as.matrix(mtcars)
 rc <- rainbow(nrow(x), start=0, end=.3)
 cc <- rainbow(ncol(x), start=0, end=.3)
hv <- heatmap.2(x, col=cm.colors(255), scale="column",
                RowSideColors=rc, ColSideColors=cc, margin=c(5, 10),
               xlab="specification variables", ylab= "Car
Models",
               main="heatmap(, ..., scale=\"column\")",
              tracecol="green", density="density")

This gives me a heatmap similar to the 9th heatmap on this page.
http://bm2.genes.nig.ac.jp/RGM2/R_current/library/gplots/man/heatmap.2.html

Now, my question is - if I wanted to increase the dimension of each cell in
this heatmap - say- from 1 inch x 2 inch to 3 inch x 4 inch ( it is OK if I
can do this in terms of pixels). Is it possible to do this ? (It is
equivalent to zooming the current heatmap)

I tried increasing the image dimension but that did not work.

I don't know if this is clear enough. Please accept my apologies in advance.

Thanks and Best Regards,
Sanvesh.

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