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Re: st: Help with mathematical operation

 From Jeph Herrin To statalist@hsphsun2.harvard.edu Subject Re: st: Help with mathematical operation Date Thu, 10 Sep 2009 15:56:31 -0400

```actually, this needs a modification in case x has
multiple instances of the same value:

local N=_N
expand _N
bysort x : gen id=mod(_n,`N')
bysort id (x) : gen y=x[id]
gen xy = x*y

hth,
Jeph

Jeph Herrin wrote:
```
```If I understand correctly (and x is your variable):

expand _N
bysort x : gen id=_n
bysort id (x) : gen y=x[id]
gen xy = x*y

will do it.

hth,
Jeph

Burnett, Tim wrote:
```
```Hello,

```
I am at the end of my tether with Stata 10 and was hoping someone could help me:
```
I have a dataset which I am trying to manipulate:

Assuming the following variable:

1
2
3
4
5
6
7
8

I am trying to create a variable which will show:

1*1
1*2
1*3
1*4
.
.
.
2*1
2*2
2*3
2*4
.
.
.
...and so on.

```
I really don't know where to look as I can't think what this mathematical operation would be called. Maybe I'm just dim.
```
Many thanks,

Tim Burnett

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