cap prog drop fig1
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prog def fig1
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glo rho=.9

di "producing fig 1.a"
cap erase 3dfig1a.gph
hidlin bivnor, x(-3 3 .2) y(-3 3 .3) e(2 -3 .5) b c sav(3dfig1a)

di "producing fig 1.b"
cap erase 3dfig1b.gph
hidlin bivnor, x(-3 3 .10) y(-3 3 .15) e(-2 -4 .3) b c l(y) sav(3dfig1b)

di "producing fig 1.c"
cap erase 3dfig1c.gph
gph open, saving(3dfig1c)
 gph font 1500 750
 gph text  9000 16000 0 0 The bivariate normal distribution
 gph font 1000 500
 gph text 14000 16000 0 0 with rho=0.9
gph close

di "producing fig 1.d"
cap erase 3dfig1d.gph
altitude bivnor, x(-3 3 .06) y(-3 3 .12) s(5) sav(3dfig1d)

di "producing fig 1"
cap erase 3dfig1.gph
gr using 3dfig1a 3dfig1b 3dfig1c 3dfig1d, saving(3dfig1)
end
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