st: estpost tabulate

[Miranda Kim <mk@mrc.soton.ac.uk>]

I am trying to add an extra column and row in a table using estpost as 
follows:

sysuse auto, clear
xtile mpg3 = mpg, nq(3)
xtile weight3 = weight, nq(3)

eststo: estpost tabulate mpg3 weight3, nototal
esttab, cell(b pct(fmt(3))) unstack noobs nonum coll(none)

I would like to add to following percentage totals:
mat totU = el(e(pct),1,4) + el(e(pct),1,7) + el(e(pct),1,8)
mat totL = el(e(pct),1,2) + el(e(pct),1,3) + el(e(pct),1,6)
mat totD = el(e(pct),1,1) + el(e(pct),1,5) + el(e(pct),1,9)

where totU would be in row 1 column 4
totL in row 4 column 1
and totD in row 4 column 4
But I have not succeeded in adding these extra column 4 and row 4 into 
the table.
I have tried using estadd, but have not achieved it yet.
I tried
mat colname totU = 4:1
estadd mat totU: est1

Any suggestions on this would be of great help!
Thanks a lot!
Best wishes,
Miranda


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