Linear equation system with uncertainties

Roofit and RooStats
1

Hello,

I have no experience with RooFit
I have to solve an equation system like (just an example)

I) x + y= 10+/-2
II) (2+/-0.2)*x + (3+/-0.3)*y = 20+/-3

I have to determine x and y but of course with respect to all uncertainties.
Can I do this with RooFit and if yes, how can I start?

Thanks!
Gordon

2

Hi,

I don’t understand why you want to use RooFit for something like this.
Just solve your system for x and y and then use error propagation for estimating the uncertainties

Lorenzo

3

Hi,

thanks for answer!
Of course I can solve the problem and use error propagation.
But at the end I have to solve a 12x12 system which is quit more complicated.
I just wanted to have an additional cross check.

Cheers,
Gordon

4

Hi,

solving the problem is not complicated if it is linear system. Just write in a matrix form.
For studying the uncertainties you can also use a MC method. Generate gaussian random values for the matrices, solve the linear system and then study the distribution of the solution

Lorenzo