Merge branch 'new_pointwise_functionality' into 'NIFTy_7'

New pointwise functionality

See merge request !591

src/pointwise.py

@@ -110,6 +110,15 @@ def _softplus_helper(v):
     return fv, dfv
 
 
+def exponentiate(v, base):
+    return np.power(base, v)
+
+
+def _exponentiate_helper(v, base):
+    tmp = np.power(base, v)
+    return (tmp , np.log(base) * tmp)
+
+
 ptw_dict = {
     "sqrt": (np.sqrt, _sqrt_helper),
     "sin": (np.sin, lambda v: (np.sin(v), np.cos(v))),
@@ -131,5 +140,6 @@ ptw_dict = {
     "sign": (np.sign, _sign_helper),
     "power": (np.power, _power_helper),
     "clip": (np.clip, _clip_helper),
-    "softplus": (softplus, _softplus_helper)
+    "softplus": (softplus, _softplus_helper),
+    "exponentiate": (exponentiate, _exponentiate_helper)
     }

test/test_linearization.py

@@ -55,7 +55,8 @@ def test_special_gradients():
 
 @pmp('f', [
     'log', 'exp', 'sqrt', 'sin', 'cos', 'tan', 'sinc', 'sinh', 'cosh', 'tanh',
-    'absolute', 'reciprocal', 'sigmoid', 'log10', 'log1p', 'expm1', 'softplus'
+    'absolute', 'reciprocal', 'sigmoid', 'log10', 'log1p', 'expm1', 'softplus',
+    ('power', 2.), ('exponentiate', 1.1)
 ])
 @pmp('cplxpos', [True, False])
 @pmp('cplxdir', [True, False])
@@ -77,8 +78,10 @@ def test_actual_gradients(f, cplxpos, cplxdir, holomorphic):
         eps *= (1+0.78j)
     var0 = ift.Linearization.make_var(fld)
     var1 = ift.Linearization.make_var(fld + eps)
-    f0 = var0.ptw(f).val.val
-    f1 = var1.ptw(f).val.val
+    if not isinstance(f, tuple):
+        f = (f,)
+    f0 = var0.ptw(*f).val.val
+    f1 = var1.ptw(*f).val.val
+    df1 = _lin2grad(var0.ptw(*f))
     df0 = (f1 - f0)/eps
-    df1 = _lin2grad(var0.ptw(f))
     assert_allclose(df0, df1, rtol=100*np.abs(eps))