change PPF switch parameter to give closer to fluid model in extreme …

…modes; changes results, but very similar near LCDM

camb/__init__.py

@@ -7,7 +7,7 @@
 __author__ = "Antony Lewis"
 __contact__ = "antony at cosmologist dot info"
 __url__ = "https://camb.readthedocs.io"
-__version__ = "1.5.5"
+__version__ = "1.5.6"
 
 from . import baseconfig
 

camb/dark_energy.py

@@ -113,8 +113,8 @@ class DarkEnergyPPF(DarkEnergyEqnOfState):
     (`arXiv:0808.3125 <https://arxiv.org/abs/0808.3125>`_)
     Use inherited methods to set parameters or interpolation table.
 
-    Note PPF is not a physical model and just designed to allow crossing -1 in an ad hoc way. For models
-    with w>-1 but far from cosmological constant, it can give quite different answers to the well-defined fluid model.
+    Note PPF is not a physical model and just designed to allow crossing -1 in an ad hoc smooth way. For models
+    with w>-1 but far from cosmological constant, it can give quite different answers to the fluid model with c_s^2=1.
 
     """
     # cannot declare c_Gamma_ppf directly here as have not defined all fields in DarkEnergyEqnOfState (TCubicSpline)

fortran/DarkEnergyPPF.f90

@@ -129,7 +129,9 @@ subroutine TDarkEnergyPPF_PerturbedStressEnergy(this, dgrhoe, dgqe, &
     S_Gamma = grhov_t * (1 + w) * (vT + sigma) * k / adotoa / 2._dl / k2
     ckH = this%c_Gamma_ppf * k / adotoa
 
-    if (ckH * ckH .gt. 3.d1) then ! ckH^2 > 30 ?????????
+    if (ckH * ckH > 1000) then
+        ! Was ckH^2 > 30 originally, but this is better behaved (closer to fluid)
+        ! for some extreme models (thanks Yanhui Yang, Simeon Bird 2024)
         Gamma = 0
         Gammadot = 0.d0
     else

fortran/config.f90

@@ -3,7 +3,7 @@ module config
     use constants, only: const_twopi
     implicit none
 
-    character(LEN=*), parameter :: version = '1.5.5'
+    character(LEN=*), parameter :: version = '1.5.6'
 
     integer :: FeedbackLevel = 0 !if >0 print out useful information about the model