Feature/lf additional models

src/lfkit/luminosity_functions/conditional_models.py

@@ -72,6 +72,9 @@ def _conditional_model_name(name: str) -> str:
     Returns:
         Conditional model name prefixed with ``"conditional_"``.
     """
+    if name.endswith("_lf"):
+        name = name.removesuffix("_lf")
+
     return f"conditional_{name}"
 
 

src/lfkit/luminosity_functions/integrals.py

@@ -320,9 +320,11 @@ def luminosity_weight(
         raise ValueError("m_reference must be finite.")
 
     absolute_mag_arr = validate_array(absolute_mag, name="absolute_mag")
-    weight = 10.0 ** (-0.4 * (absolute_mag_arr - m_reference))
-    weight = np.clip(weight, 1e-300, 1e300)
 
+    exponent = -0.4 * (absolute_mag_arr - m_reference)
+    exponent = np.clip(exponent, -300.0, 300.0)
+
+    weight = 10.0**exponent
     return np.asarray(weight, dtype=float)
 
 

src/lfkit/luminosity_functions/models/gamma.py

@@ -0,0 +1,145 @@
+r"""Gamma-family luminosity function models.
+
+This module provides standalone functions for evaluating gamma-like luminosity
+function models in rest frame absolute magnitude space.
+
+Implemented models:
+    - Gamma luminosity function
+    - Generalized gamma luminosity function
+"""
+
+from __future__ import annotations
+
+import numpy as np
+
+from lfkit.utils.integrators import safe_power10
+from lfkit.utils.types import FloatArray, FloatInput, ParameterValue
+from lfkit.utils.validators import validate_array
+
+
+__all__ = [
+    "gamma_lf",
+    "generalized_gamma_lf",
+]
+
+
+def gamma_lf(
+    absolute_mag: FloatInput,
+    *,
+    phi_star: ParameterValue,
+    m_star: ParameterValue,
+    alpha: ParameterValue,
+) -> FloatArray:
+    r"""Return a gamma luminosity function in magnitude space.
+
+    This computes
+
+    .. math::
+
+        \phi(M) =
+        0.4 \ln(10) \, \phi_\star \,
+        x^{\alpha + 1} \exp(-x),
+
+    where
+
+    .. math::
+
+        x = 10^{-0.4(M - M_\star)}.
+
+    This is mathematically equivalent to the standard Schechter luminosity
+    function, but is provided as a gamma-family model for users who want to
+    describe the luminosity function as a gamma distribution in luminosity
+    space.
+
+    Args:
+        absolute_mag: Absolute magnitude value(s).
+        phi_star: Gamma luminosity function normalization.
+        m_star: Characteristic magnitude.
+        alpha: Low-luminosity power-law slope.
+
+    Returns:
+        NumPy array containing the gamma luminosity function evaluated at
+        ``absolute_mag``.
+
+    Raises:
+        ValueError: If ``phi_star`` is negative.
+    """
+    absolute_mag_arr = validate_array(absolute_mag, name="absolute_mag")
+    phi_star_arr = validate_array(phi_star, name="phi_star")
+    alpha_arr = validate_array(alpha, name="alpha")
+
+    if np.any(phi_star_arr < 0.0):
+        raise ValueError("phi_star must be non-negative.")
+
+    x = safe_power10(-0.4 * (absolute_mag_arr - m_star))
+
+    phi = 0.4 * np.log(10.0) * phi_star_arr * x ** (alpha_arr + 1.0) * np.exp(-x)
+
+    return np.asarray(phi, dtype=float)
+
+
+def generalized_gamma_lf(
+    absolute_mag: FloatInput,
+    *,
+    phi_star: ParameterValue,
+    m_star: ParameterValue,
+    alpha: ParameterValue,
+    beta: ParameterValue,
+) -> FloatArray:
+    r"""Return a generalized gamma luminosity function in magnitude space.
+
+    This computes
+
+    .. math::
+
+        \phi(M) =
+        0.4 \ln(10) \, \beta \, \phi_\star \,
+        x^{\alpha + 1} \exp(-x^\beta),
+
+    where
+
+    .. math::
+
+        x = 10^{-0.4(M - M_\star)}.
+
+    The gamma or Schechter form is recovered when ``beta = 1``. Values
+    ``beta < 1`` produce a shallower bright-end cutoff, while values
+    ``beta > 1`` produce a sharper bright-end cutoff.
+
+    Args:
+        absolute_mag: Absolute magnitude value(s).
+        phi_star: Generalized gamma luminosity function normalization.
+        m_star: Characteristic magnitude.
+        alpha: Low-luminosity power-law slope.
+        beta: Positive bright-end cutoff shape parameter.
+
+    Returns:
+        NumPy array containing the generalized gamma luminosity function
+        evaluated at ``absolute_mag``.
+
+    Raises:
+        ValueError: If ``phi_star`` is negative or if ``beta`` is not positive.
+    """
+    absolute_mag_arr = validate_array(absolute_mag, name="absolute_mag")
+    phi_star_arr = validate_array(phi_star, name="phi_star")
+    alpha_arr = validate_array(alpha, name="alpha")
+    beta_arr = validate_array(beta, name="beta")
+
+    if np.any(phi_star_arr < 0.0):
+        raise ValueError("phi_star must be non-negative.")
+
+    if np.any(beta_arr <= 0.0):
+        raise ValueError("beta must be positive.")
+
+    x = safe_power10(-0.4 * (absolute_mag_arr - m_star))
+
+    phi = (
+        0.4
+        * np.log(10.0)
+        * beta_arr
+        * phi_star_arr
+        * x ** (alpha_arr + 1.0)
+        * np.exp(-(x**beta_arr))
+    )
+
+    return np.asarray(phi, dtype=float)