multimeter/voltmeter now raise an exception if one tries to set a recording interval that is not a multiple of the resolution

models/multimeter.cpp

@@ -129,39 +129,34 @@ nest::multimeter::Parameters_::set( const DictionaryDatum& d, const Buffers_& b,
       "to nodes." );
   }
 
-  double v;
-  if ( updateValueParam< double >( d, names::interval, v, node ) )
+  double interval_ms;
+  if ( updateValueParam< double >( d, names::interval, interval_ms, node ) )
   {
-    if ( Time( Time::ms( v ) ) < Time::get_resolution() )
+    interval_ = Time( Time::ms( interval_ms ) );
+    if ( interval_ < Time::get_resolution() )
     {
-      throw BadProperty(
-        "The sampling interval must be at least as long "
-        "as the simulation resolution." );
+      throw BadProperty( "The sampling interval must be at least as long as the simulation resolution." );
     }
 
-    // see if we can represent interval as multiple of step
-    interval_ = Time::step( Time( Time::ms( v ) ).get_steps() );
     if ( not interval_.is_multiple_of( Time::get_resolution() ) )
     {
-      throw BadProperty(
-        "The sampling interval must be a multiple of "
-        "the simulation resolution" );
+      throw BadProperty( "The sampling interval must be a multiple of the simulation resolution." );
     }
   }
 
-  if ( updateValueParam< double >( d, names::offset, v, node ) )
+  if ( updateValueParam< double >( d, names::offset, interval_ms, node ) )
   {
     // if offset is different from the default value (0), it must be at least
     // as large as the resolution
-    if ( v != 0 and Time( Time::ms( v ) ) < Time::get_resolution() )
+    if ( interval_ms != 0 and Time( Time::ms( interval_ms ) ) < Time::get_resolution() )
     {
       throw BadProperty(
         "The offset for the sampling interval must be at least as long as the "
         "simulation resolution." );
     }
 
     // see if we can represent offset as multiple of step
-    offset_ = Time::step( Time( Time::ms( v ) ).get_steps() );
+    offset_ = Time::step( Time( Time::ms( interval_ms ) ).get_steps() );
     if ( not offset_.is_multiple_of( Time::get_resolution() ) )
     {
       throw BadProperty(

models/multimeter.h

@@ -72,11 +72,12 @@ recordables to have them sampled during simulation.
 The sampling interval for recordings (given in ms) can be controlled
 using the ``multimeter`` parameter ``interval``. The default value of
 1.0 ms can be changed by supplying a new value either in the call to
-``Create`` or by using ``SetStatus`` on the model instance.
+``Create`` or by using ``SetStatus`` on the model instance. To sample
+ values at every simulation time step, use
 
 ::
 
-   nest.SetStatus(mm, {'interval': 0.1})
+   nest.SetStatus(mm, {'interval': nest.resolution})
 
 The recording interval must be greater than or equal to the
 :ref:`simulation resolution <simulation_resolution>`, which defaults
@@ -121,6 +122,7 @@ record_from
 interval
     A float (default: 1.0) specifying the interval in ms, at which
     data is collected from the nodes, the multimeter is connected to.
+    Must be a multiple of the resolution.
 
 See also
 ++++++++

testsuite/pytests/test_multimeter.py

@@ -126,3 +126,13 @@ def test_identical_recording_from_multiple_multimeters(model):
 
     for recordable in recordables:
         nptest.assert_array_equal(mm1.events[recordable], mm2.events[recordable])
+
+
+@pytest.mark.parametrize("interval", [0, 0.05, 0.15])
+def test_bad_intervals_detected(interval):
+    """
+    Test that NEST raises BadProperty if interval cannot be represented as multiple of resolution.
+    """
+
+    with pytest.raises(nest.kernel.NESTError, match="BadProperty"):
+        nest.Create("multimeter", params={"interval": interval})