sh and py install scripts

install_classy.sh

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+#! /bin/bash
+set -e  # Exit immediately if a command exits with a non-zero status
+set -u  # Treat unset variables as an error
+set -o pipefail  # Pipeline fails on any command failure
+
+echo "=== Starting CLASS installation process ==="
+echo "Current directory: $(pwd)"
+echo "Contents of directory: $(ls -la)"
+
+# Git clone class only if the directory doesn't exist yet
+if [ ! -d "class_public" ]; then
+    echo "=== Cloning CLASS repository ==="
+    git clone --depth 1 --single-branch --branch master https://github.com/lesgourg/class_public.git
+else
+    echo "=== CLASS repository already exists, skipping clone ==="
+fi
+
+# Change to the class_public directory
+echo "=== Changing to class_public directory ==="
+if [ ! -d "class_public" ]; then
+    echo "ERROR: class_public directory not found!"
+    exit 1
+fi
+
+cd class_public/
+echo "Now in: $(pwd)"
+echo "Contents of class_public: $(ls -la)"
+
+# Clean previous builds
+echo "=== Cleaning previous build ==="
+make clean || echo "Clean step failed, but continuing..."
+
+# Install dependencies
+echo "=== Installing Python dependencies ==="
+echo "Installing numpy..."
+pip install "numpy<=1.26" -v || { echo "Failed to install numpy"; exit 1; }
+
+echo "Installing scipy..."
+pip install "scipy" -v || { echo "Failed to install scipy"; exit 1; }
+
+echo "Installing Cython..."
+pip install "Cython" -v || { echo "Failed to install Cython"; exit 1; }
+
+# Build CLASS
+echo "=== Building CLASS library ==="
+make -j || { echo "Failed to build CLASS"; exit 1; }
+
+# Install the Python module
+#echo "=== Installing CLASS Python module ==="
+#pip install . -v || { echo "Failed to install CLASS Python module"; exit 1; }
+
+# Verify installation
+#echo "=== Verifying installation ==="
+#python3 -c "from classy import Class; print('CLASS successfully imported!')" || { echo "Failed to import CLASS in Python"; exit 1; }
+
+echo "=== CLASS installation completed successfully ==="
+exit 0

test_classy.py

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+# Import necessary modules
+from classy import Class
+import matplotlib.pyplot as plt
+import numpy as np
+
+# Define common settings for the ΛCDM model, including a fixed Helium fraction
+common_settings = {
+    'h': 0.67810,
+    'omega_b': 0.02238280,
+    'omega_cdm': 0.1201075,
+    'A_s': 2.100549e-09,
+    'n_s': 0.9660499,
+    'tau_reio': 0.05430842,
+    'YHe': 0.24,  # Set the Helium fraction explicitly
+    'output': 'tCl,lCl',  # Include 'lCl' for lensing potential
+    'lensing': 'yes',
+    'l_max_scalars': 2500
+}
+
+# Initialize CLASS
+cosmo = Class()
+cosmo.set(common_settings)
+cosmo.compute()
+
+# Get the C_l's
+cls = cosmo.lensed_cl(2500)
+
+# Extract ell and C_ell^TT
+ell = cls['ell'][2:]  # Start from 2 to avoid the monopole and dipole
+clTT = cls['tt'][2:]
+
+# Plotting
+factor = ell * (ell + 1) / (2 * np.pi) * 1e12  # Factor to convert to D_ell
+
+plt.plot(ell, factor * clTT, label='Temperature $C_\ell^{TT}$', color='b')
+plt.xlabel(r'Multipole moment $\ell$')
+plt.ylabel(r'$\ell (\ell + 1) C_\ell^{TT} / 2\pi \, [\mu K^2]$')
+plt.title('CMB Temperature Power Spectrum')
+plt.xscale('log')
+plt.yscale('log')
+plt.grid(True)
+plt.legend()
+plt.savefig('cmb_temperature_spectrum.png')  # Save the plot to a file