Theory

Theoretical Background

The physics, derivations, and conventions behind NumCosmo’s models. Each page is linked from the corresponding API documentation, and links back to the relevant classes and methods.

Background & Thermal History

• Cosmological Distances — comoving, transverse, luminosity, and angular diameter distances.
• Cosmic Recombination — Saha equilibrium, the Seager solver, optical depth and visibility.

Linear Theory & Power Spectrum

• Eisenstein–Hu Transfer Function — the EH (1998) fitting formula, with and without baryons.

Clusters & Weak Lensing

• Halo Density Profiles — NFW, Einasto, and Hernquist profiles and their projected quantities.
• Weak-Lensing Surface Mass Density — projected surface density, convergence, and shear.
• Galaxy Shapes and Ellipticity Frames — the shape forward model, ellipticity conventions, and the celestial/Euclidean handedness frames.

Numerical Methods

• FFTLog — logarithmic fast Fourier transform.
• Spectral Methods — Chebyshev approximation, Clenshaw–Curtis integration, and ultraspherical operators.
• CSQ1D Formalism — complex-structure evolution of a time-dependent oscillator.