t-distribution

[jolly]

I have to generate errors which are distributed as a Student t-distribution and I use function @rtdist(v). How I should choose value of degrees "v"?

[startz]

That would depend on what you're trying to do...

[jolly]

I'm creating a regresion, and it's is said that errors e~t(v).and nothing about "v" ..

[startz]

Then there's no way to know what value to use, other than it has to be positive. If the value is large, say 120+ you're essentially getting normal errors. Since whoever made up the assignment specified t-, they probably want a smallish integer.