Quickstart Guide

Quickstart Guide#

Warning

Demonstration Package This is a demonstration package created for a course on Scientific Software Development. The package and its documentation are designed to showcase best practices in scientific software development. This is not a real cosmology package and should not be used in actual research.

This guide will help you get started with using the mycosmo package for cosmological calculations.

Installation#

First, install the package using pip:

pip install mycosmo

Basic Usage#

The package provides two main functions for cosmological calculations:

  1. hubble: Calculate the Hubble parameter at a given redshift

  2. critical_density: Calculate the critical density at a given redshift

Example: Calculating the Hubble Parameter#

Here’s how to calculate the Hubble parameter at different redshifts:

import numpy as np
from mycosmo.cosmology import hubble

# Define cosmological parameters
cosmo_dict = {
    "H0": 70,  # km/s/Mpc
    "omega_m_0": 0.3,
    "omega_k_0": 0.0,
    "omega_lambda_0": 0.7
}

# Calculate H(z) at z = 0
H0 = hubble(0.0, cosmo_dict)
print(f"H0 = {H0:.2f} km/s/Mpc")

# Calculate H(z) at multiple redshifts
z = np.array([0.5, 1.0, 2.0])
H_z = hubble(z, cosmo_dict)
for z_val, H_val in zip(z, H_z):
    print(f"H(z={z_val}) = {H_val:.2f} km/s/Mpc")

Example: Calculating Critical Density#

To calculate the critical density at different redshifts:

from mycosmo.cosmology import critical_density

# Calculate ρ_c(z) at z = 0
rho_c0 = critical_density(0.0, cosmo_dict)
print(f"ρ_c(0) = {rho_c0:.2e} kg/m³")

# Calculate ρ_c(z) at multiple redshifts
rho_c = critical_density(z, cosmo_dict)
for z_val, rho_val in zip(z, rho_c):
    print(f"ρ_c(z={z_val}) = {rho_val:.2e} kg/m³")

Cosmological Parameters#

The package uses a dictionary to specify cosmological parameters. The required parameters are:

  • H0: Hubble constant at z=0 (km/s/Mpc)

  • omega_m_0: Matter density parameter at z=0

  • omega_k_0: Curvature density parameter at z=0

  • omega_lambda_0: Dark energy density parameter at z=0

Constants#

The package provides some useful cosmological constants in the mycosmo.constants module:

  • G: Gravitational constant

  • Mpc: Megaparsec in meters

You can use these constants in your calculations:

from mycosmo.constants import G, Mpc

# Example: Convert H0 from km/s/Mpc to s^-1
H0_si = 70 * 1000 / Mpc  # Convert to s^-1

Advanced Usage#

For more advanced usage, including:

  • Custom cosmological models

  • Additional cosmological calculations

  • Integration with other scientific packages

Please refer to the full API documentation in the mycosmo section.

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