### Constrained Base Parameters in CosmoMC

Posted:

**July 03 2020**Dear All,

In a non-standard cosmological model two base parameters X and Y are theoretically constrained via the equation Y=F(X), where F is some simple

(and known) algebraic function (so X and Y cannot be independently drawn from their respective flat prior distributions) . Specifically, in my case Y is the spectral tilt of scalar perturbations, n_s, and X is the dark energy equation of state w. What is the best way to impose this theoretical constraint in CosmoMC ?

Any help with this matter (for a non-f90-expert) would be much appreciated.

Thanks,

Meir

In a non-standard cosmological model two base parameters X and Y are theoretically constrained via the equation Y=F(X), where F is some simple

(and known) algebraic function (so X and Y cannot be independently drawn from their respective flat prior distributions) . Specifically, in my case Y is the spectral tilt of scalar perturbations, n_s, and X is the dark energy equation of state w. What is the best way to impose this theoretical constraint in CosmoMC ?

Any help with this matter (for a non-f90-expert) would be much appreciated.

Thanks,

Meir