Merge branch 'log_invgamma' into 'NIFTy_7'

Log invgamma

See merge request !614

src/__init__.py

@@ -77,7 +77,8 @@ from .sugar import *
 
 from .plot import Plot
 
-from .library.special_distributions import InverseGammaOperator, UniformOperator, LaplaceOperator
+from .library.special_distributions import InverseGammaOperator, \
+    UniformOperator, LaplaceOperator, LogInverseGammaOperator
 from .library.los_response import LOSResponse
 from .library.dynamic_operator import (dynamic_operator,
                                        dynamic_lightcone_operator)

src/library/special_distributions.py

@@ -124,6 +124,20 @@ def InverseGammaOperator(domain, alpha, q, delta=1e-2):
     return makeOp(q) @ op
 
 
+def LogInverseGammaOperator(domain, alpha, q, delta=1e-2):
+    """Transform a standard normal into the log of an inverse gamma distribution.
+
+    See also
+    --------
+    :class:`InverseGammaOperator`
+    """
+    op = _InterpolationOperator(domain, lambda x: np.log(invgamma.ppf(norm._cdf(x), float(alpha))),
+                                -8.2, 8.2, delta)
+    if np.isscalar(q):
+        return op.scale(q)
+    return makeOp(q) @ op
+
+
 class UniformOperator(Operator):
     """Transform a standard normal into a uniform distribution.
 

src/pointwise.py

@@ -11,7 +11,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
-# Copyright(C) 2020 Max-Planck-Society
+# Copyright(C) 2020-2021 Max-Planck-Society
 # Author: Martin Reinecke
 #
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik.
@@ -124,7 +124,7 @@ def exponentiate(v, base):
 
 def _exponentiate_helper(v, base):
     tmp = np.power(base, v)
-    return (tmp , np.log(base) * tmp)
+    return (tmp, np.log(base) * tmp)
 
 
 ptw_dict = {

test/test_operators/test_jacobian.py

@@ -95,6 +95,8 @@ def testInverseGamma(space, seed):
         q = 0.73
         model = ift.InverseGammaOperator(space, alpha, q)
         ift.extra.check_operator(model, pos, ntries=20)
+        model = ift.LogInverseGammaOperator(space, alpha, q)
+        ift.extra.check_operator(model, pos, ntries=20)
 
 
 @pmp("loc", [0, 13.2])