other ODE integrators in CAMB

Use of Healpix, camb, CLASS, cosmomc, compilers, etc.
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Erick Almaraz
Posts: 26
Joined: June 10 2012
Affiliation: University of Mexico

other ODE integrators in CAMB

Post by Erick Almaraz » December 06 2018

Dear Cosmo Coffee forum,

I am implementing an alternative DE model in CAMB. However, the dynamical background equations seem to be stiff and the default integrator dverk available in $CAMB/subroutines.f90 is not able to solve these equations. On the other hand, these same equations can be solved numerically in python & mathematica. I have heard that there is a special library (ODEPACK) written in fortran 77 with which is possible to solve stiff equations. Is it possible to plug this library into CAMB, so that we can use the subroutines therein to solve stiff ODES?


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Antony Lewis
Posts: 1394
Joined: September 23 2004
Affiliation: University of Sussex
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Re: other ODE integrators in CAMB

Post by Antony Lewis » December 07 2018

There's not built-in support for different integrators, but it should be relatively straightforward to replace dverk with another one.

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