There are two ways of building initial conditions for models which are not provided with the package.

- 1.
- You may add a line to
**cdm.fit**with fitting parameters for your model and with parameters of approximation for the power spectrum. This requires that your model is well fit by our fitting formula (eq. 20). The format of the**cdm.fit**file is described in the file. See also the routine**TRUNF(k)**for details of the approximation of the power spectrum of perturbations. - 2.
- You may change the functions TRUNF in
**PMstartCDM.f**and Pk in**PMmodels.f**to return whatever initial spectra you desire.