> dgeom(4, .2)
[1] 0.08192
> dgeom(0:4, .2)
[1] 0.20000 0.16000 0.12800 0.10240 0.08192
> sum(dgeom(0:4, .2))
[1] 0.67232

> pgeom(4, .2, lower.tail=T)
[1] 0.67232
> 
> pgeom(4, .2, lower.tail=F)
[1] 0.32768
> 
> sum(dgeom(5:1000000, .2))
[1] 0.32768
> 
> 
> pgeom(4, .2, lower.tail=T)+pgeom(4, .2, lower.tail=F)
[1] 1

> qgeom(.5, .2)
[1] 3
> pgeom(3, .2)
[1] 0.5904
> qgeom(.6, .2)
[1] 4
> 
> qgeom(1, .2)
[1] Inf
> qgeom(.2, .2)
[1] 0
>