Quick Start Guide

Using FAST-PT is straightforward. Here’s a simple example to get started:

import numpy as np
import matplotlib.pyplot as plt
from fastpt import FASTPT, FPTHandler

#Define a k range
k = np.logspace(1e-4, 1, 1000)

# Initialize FASTPT
fpt = FASTPT(k, low_extrap=-5, high_extrap=3, n_pad=int(0.5*len(k)))
handler = FPTHandler(fpt)

# Use the handler to generate a power spectrum
P = handler.generate_power_spectra()

# Calculate an individual term using the handler
P_1loop = handler.get("P_1loop", P=P)

# Store default parameters
handler.update_default_params(P=P, P_window=np.array([0.2, 0.2]), C_window=0.75)

# Use the stored parameters in a calculation
tt_result = handler.run("IA_tt")

# Or get the result directly
tt_direct = fpt.IA_tt(P=P, P_window=np.array([0.2, 0.2]), C_window=0.75)

# Plot the results
handler.plot(data=tt_result)

NOTE: This code uses the FPTHandler class to simplify the process of generating power spectra and calculating specific terms. However, the handler is not needed for any FAST-PT calculations. It simply provides a convenient interface for common tasks and integration with relevant libraries like matplotlib, CAMB, and CLASS.