Refactored evaluation of global expressions.

In parametric sweeps where the number of time steps depends on the
parameter, the number of time steps returned always corresponded
to the first outer solution, i.e. the first parameter value. In
evaluations of other outer solutions, the additional time steps were
then missing. See issue MPh-py#112.

We now use an `EvalGlobal` feature instead of a `Global` evaluation
feature, and call `computeResult` instead of `getData`. This fixes
the issue, though it is not clear (to me) from the Comsol API
documentation why the two feature types and method calls behave
differently.

https://doc.comsol.com/6.1/doc/com.comsol.help.comsol/api/com/comsol/model/NumericalFeature.html

mph/model.py

@@ -526,7 +526,7 @@ def evaluate(self, expression, unit=None, dataset=None,
             raise RuntimeError(error)
 
         # Try to perform a global evaluation, which may fail.
-        eval = (self/'evaluations').create('Global')
+        eval = (self/'evaluations').create('EvalGlobal')
         eval.property('expr', expression)
         if unit:
             eval.property('unit', unit)
@@ -536,26 +536,28 @@ def evaluate(self, expression, unit=None, dataset=None,
         try:
             log.debug('Trying global evaluation.')
             java = eval.java
-            results = array(java.getData())
+            results = array(java.computeResult())
             if java.isComplex():
-                results = results.astype('complex')
-                results += 1j * array(java.getImagData())
-            eval.remove()
+                results = results[0].astype('complex') + 1j*results[1]
+            else:
+                results = results[0]
             log.info('Finished global evaluation.')
             if inner is None:
                 pass
             elif inner == 'first':
-                results = results[:, 0, :]
+                results = results[0]
             elif inner == 'last':
-                results = results[:, -1, :]
+                results = results[-1]
             else:
                 if isinstance(inner, list):
                     inner = array(inner)
-                results = results[:, inner-1, :]
+                results = results[inner-1]
             return results.squeeze()
         # Move on if this fails. Seems to not be a global expression then.
         except Exception:
             log.debug('Global evaluation failed. Moving on.')
+        finally:
+            eval.remove()
 
         # For particle datasets, create an "EvalPoint" feature.
         if dataset.type() == 'Particle':

tests/test_model.py

@@ -320,6 +320,13 @@ def test_evaluate():
     D = model.evaluate(expression, unit, dataset, outer=2)
     assert (D[0]  == Df).all()
     assert (D[-1] == Dl).all()
+    # Test varying time steps in parameter sweep. See issue #112.
+    study = model/'studies'/'sweep'
+    (study/'time-dependent').property('tlist', 'range(0, 0.01/d[1/mm], 1)')
+    model.solve(study)
+    assert len(model.evaluate('t', 's', 'parametric sweep', outer=1)) == 101
+    assert len(model.evaluate('t', 's', 'parametric sweep', outer=2)) == 201
+    assert len(model.evaluate('t', 's', 'parametric sweep', outer=3)) == 301
     # Test evaluation of complex-valued global expressions.
     U = model.evaluate('U')
     z = model.evaluate('U + j*U')