### Adding a perturbation discontinuity in CAMB

Posted:

**March 15 2022**Hi everyone,

I am not an expert on CAMB, and currently I'm trying to introduce a model like the one on https://arxiv.org/pdf/2006.06686.pdf (in specific eqs. 85) where at an $a_{critic}$ some Early Dark Energy perturbations change immediatly from a value $0$ to some value $\delta^*$, $\theta^*$.

The problem is that when I manually try to introduce on camb ay(w_ix)$=\delta^*$, ay(w_ix+1)$=\theta^*$ when $\text{abs}(a-a_{critic})<\varepsilon$, I get a compilation time extremely large or directly I get the following error
Is there some hack or any other way to define this perturbation discontinuities? Thanks in advance for your help

I am not an expert on CAMB, and currently I'm trying to introduce a model like the one on https://arxiv.org/pdf/2006.06686.pdf (in specific eqs. 85) where at an $a_{critic}$ some Early Dark Energy perturbations change immediatly from a value $0$ to some value $\delta^*$, $\theta^*$.

The problem is that when I manually try to introduce on camb ay(w_ix)$=\delta^*$, ay(w_ix+1)$=\theta^*$ when $\text{abs}(a-a_{critic})<\varepsilon$, I get a compilation time extremely large or directly I get the following error

Code: Select all

```
Dverk error -3: the subroutine was unable to satisfy the error requirement with a particular step-size that is less than or * equal to hmin, which may mean that tol is too small--- but most likely you've messed up the y array indexing; compiling with bounds checking may (or may not) help find the problem.
Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG
ERROR STOP Invalid parameter
Error termination. Backtrace:
#0 0x10353d147
#1 0x10353ddbf
#2 0x10353f0ab
#3 0x10303034f
#4 0x103053e07
```