Merge pull request #91 from joezuntz/s8_sample

Allow sampling in S_8

.github/workflows/ci.yml

@@ -152,7 +152,7 @@ jobs:
         run: |
           source cosmosis-configure
           cosmosis examples/des-y3-shear.ini | tee output/des-y3-shear.log
-          grep -e 'Likelihood =  2957.03' -e 'Likelihood =  2957.12' output/des-y3-shear.log
+          grep -e 'Likelihood =  2957.03' -e 'Likelihood =  2957.12' -e 'Likelihood =  2957.11' output/des-y3-shear.log
 
 
       - name: DES Y3 likelihood with Mira Titan

examples/des-y3-shear-values.ini

@@ -3,9 +3,13 @@ omega_m      =  0.1     0.3     0.9
 h0           =  0.55    0.69    0.91
 omega_b      =  0.03    0.048   0.07
 n_s          =  0.87    0.97    1.07
-A_s          =  0.5e-09 2.19e-9 5.0e-09
 w            =  -1.0
 
+; This is here to test S_8 sampling, not to recommend it.
+; Don't just put a flat prior on whatever the most convenient
+; parameter is.
+S_8          =  0.7    0.8256338136297622   0.84
+
 ; Old parameter names from original cosmosis version
 ; omnuh2       =  0.0006  0.00083 0.00644
 ; massive_nu   =  3

utility/consistency/consistency_interface.py

@@ -71,4 +71,16 @@ def execute(block, config):
             section = cosmo
         block[section, param] = value
 
+    if block.has_value(cosmo, "S_8") and block.has_value(cosmo, "omega_m"):
+        sigma_8 = block[cosmo, "S_8"] / (block[cosmo, "omega_m"] / 0.3)**0.5
+
+        if block.has_value(cosmo, "sigma_8"):
+            sigma8_check = block[cosmo, 'sigma_8']
+            if not np.isclose(sigma_8, sigma8_check):
+                raise ValueError("Inconsistent values of sigma_8 and S_8.")
+        elif cons.verbose:
+            print(f"Calculated sigma_8 = {sigma_8} from S_8/(Omega_m/0.3)**0.5")
+
+        block[cosmo, "sigma_8"] = sigma_8
+
     return 0