gh-507: Pull request to integrate mg binned boost emulator

cloelib/cosmology/README_binned.md

@@ -0,0 +1,230 @@
+# Modified Gravity Euclid Module (CLOE Integration)
+
+This module implements modified gravity (MG) perturbations for Euclid-like analyses using a binned MG emulator. It is designed to be fully compatible with the `cloelib` cosmology and likelihood framework.
+
+The core component is the `MGPerturbations` class, which wraps an emulator-based boost model and applies it to standard ΛCDM linear and nonlinear matter power spectra.
+
+---
+
+## Installation
+
+You need to clone the parent repo that contains the emulator files and down the models from Zenodo.
+
+```python
+https://github.com/sankarshana16/mg_binned_boost_emulator.git
+```
+
+You can find the models in
+
+```
+[Zenodo Dataset](https://zenodo.org/records/19625918)
+```
+
+After downloading, place all files in:
+
+```bash
+mg_binned_boost_emulator/models/
+```
+
+---
+
+## 🚀 Features
+
+- Emulator-based MG boost applied to:
+  - Linear matter power spectrum
+  - Nonlinear matter power spectrum
+- Fully compatible with `cloelib` `Perturbations` interface
+- Lazy loading of emulator (loaded once per session)
+- Supports redshift-binned MG modifications
+- Provides:
+  - \( P(k, z) \)
+  - Growth factor \( D(z, k) \)
+  - Growth rate \( f(z, k) \)
+  - \( \sigma_8 \)
+  - Lensing modification \( \Sigma(z) \)
+
+---
+
+## 📦 Class Overview
+
+### `MGPerturbations`
+
+Main wrapper class implementing MG perturbations.
+
+---
+
+### Initialization
+
+    MGPerturbations(
+        background,
+        linearperturbations,
+        nonlinearperturbations,
+        redshifts,
+        mu,
+        eta,
+        bin_index,
+        model_dir="./models"
+    )
+
+#### Inputs
+
+| Parameter                | Description                    |
+| ------------------------ | ------------------------------ |
+| `background`             | `cloelib` background cosmology |
+| `linearperturbations`    | Linear ΛCDM perturbations      |
+| `nonlinearperturbations` | Nonlinear ΛCDM (e.g. HMCode)   |
+| `redshifts`              | Array of redshifts             |
+| `mu`, `eta`              | Modified gravity parameters    |
+| `bin_index`              | Active MG redshift bin         |
+| `model_dir`              | Path to emulator models        |
+
+---
+
+## ⚙️ How It Works
+
+1. Convert `cloelib` cosmology → emulator format
+2. Load MG emulator (cached globally)
+3. Predict:
+   - Nonlinear boost
+   - Linear boost
+4. Apply boosts to ΛCDM spectra:
+   \( P*{\rm MG} = \text{boost} \times P*{\Lambda\rm CDM} \)
+5. Build spline interpolators for fast evaluation
+
+---
+
+## 📊 Available Methods
+
+### Matter Power Spectrum
+
+    matter_power_spectrum(zs, ks)
+
+Returns:
+
+\( P(k, z) \)
+
+---
+
+### Growth Factor
+
+    growth_factor(zs, ks)
+
+\[
+D(z, k) = \sqrt{\frac{P*{\rm lin}(z, k)}{P*{\rm lin}(0, k)}}
+\]
+
+---
+
+### Growth Rate
+
+    growth_rate(zs, ks)
+
+\[
+f(z, k) = \frac{d \ln D}{d \ln a}
+\]
+
+Computed numerically via:
+
+\[
+f = -(1+z)\frac{d\ln D}{dz}
+\]
+
+---
+
+### Sigma8
+
+    sigma8_0()
+
+\[
+\sigma*8^2 = \frac{1}{2\pi^2} \int dk\, k^2 P*{\rm lin}(k, z=0) W^2(kR)
+\]
+
+with:
+
+- \( R = 8\, \mathrm{Mpc}/h \)
+- Top-hat window function
+
+---
+
+### Lensing Modification
+
+    Sigma(zs)
+
+\[
+\Sigma = \frac{\mu(1 + \eta)}{2}
+\]
+
+Applied only within the active redshift bin.
+
+Outside the bin:
+
+\[
+\Sigma = 1
+\]
+
+---
+
+## 📦 Redshift Binning
+
+| bin_index | Redshift range |
+| --------- | -------------- |
+| 0         | 0.00 – 0.43    |
+| 1         | 0.43 – 0.91    |
+| 2         | 0.91 – 1.47    |
+| 3         | 1.47 – 2.15    |
+| 4         | 2.15 – 3.00    |
+
+---
+
+## ⚡ Performance
+
+- Emulator is loaded **once per Python session**
+- Subsequent likelihood calls reuse cached model
+- Designed for fast MCMC / nested sampling
+
+---
+
+## ⚠️ Assumptions & Limitations
+
+- Flat cosmology only (`Omega_k = 0`)
+- Emulator validity range must be respected
+- Not implemented:
+  - `matter_power_spectrum_cb`
+
+---
+
+## 🧪 Example Usage
+
+    mg = MGPerturbations(
+        background=background,
+        linearperturbations=lp,
+        nonlinearperturbations=nlp,
+        redshifts=z,
+        mu=1.0,
+        eta=1.0,
+        bin_index=1,
+    )
+
+    Pk = mg.matter_power_spectrum(z, k)
+
+---
+
+## 📁 Dependencies
+
+- numpy
+- scipy
+- cloelib
+- MG emulator (`MGEmulator`)
+
+---
+
+## 🧑‍💻 Author
+
+Sankarshana Srinivasan
+
+---
+
+## 📌 TODO
+
+- Add baryon/CDM split (`P_cb`)
+- Validate \( \sigma_8 \) normalization (h-consistency)

cloelib/cosmology/__init__.py

@@ -7,5 +7,5 @@
 Supported External Codes:
 
 - **Background**: `camb`, `class`
-- **Perturbations**: `camb`, `class`, `HMCode2020emu`
+- **Perturbations**: `camb`, `class`, `HMCode2020emu`, `euclidemu2`, `baccoemu`
 """