Check dimensions

essm/variables/_core.py

@@ -28,7 +28,7 @@
 
 from sympy import (Abs, Add, Basic, Derivative, Function, Integral, log, Mul,
                    Piecewise, Pow, S, Symbol)
-from sympy.physics.units import Dimension, Quantity, convert_to
+from sympy.physics.units import (Dimension, Quantity, convert_to)
 from sympy.physics.units.systems.si import dimsys_SI, SI
 from sympy.physics.units.util import check_dimensions
 
@@ -230,10 +230,14 @@ def collect_factor_and_basedimension(expr):
                     sum([x[0] for x in expr.args]))
             return factor, dim
         elif isinstance(expr, Function):
-            fds = [Variable.collect_factor_and_basedimension(
-                arg) for arg in expr.args]
-            return (expr.func(*(f[0] for f in fds)),
-                    expr.func(*(d[1] for d in fds)))
+            fds = set(Variable.collect_factor_and_basedimension(
+                arg)[1] for arg in expr.args)
+            if fds != {Dimension(1)}:
+                print(fds)
+                raise ValueError(
+                    'Arguments in function are not dimensionless, '
+                    'but have dimensions of {0}'.format(fds))
+            return expr, Dimension(1)
         elif isinstance(expr, Dimension):
             return 1, expr
         else:

essm/variables/units.py

@@ -165,5 +165,6 @@ def derive_base_dimension(dim):
 
 __all__ = (
     'derive_baseunit', 'derive_unit', 'markdown',
-    'joule', 'kelvin', 'kilogram', 'meter', 'mole', 'pascal', 'second', 'watt'
+    'joule', 'kelvin', 'kilogram', 'meter', 'mole',
+    'pascal', 'second', 'watt'
 )

tests/test_equations.py

@@ -11,7 +11,7 @@
                                   derive_baseunit)
 from essm.variables.utils import (extract_variables, replace_defaults,
                                   replace_variables)
-from sympy import Derivative, exp, log, S, Symbol, solve, sqrt
+from sympy import cos, Derivative, exp, log, S, Symbol, solve, sqrt
 from sympy.physics.units import Quantity, length, meter
 
 
@@ -113,6 +113,20 @@ class valid_units(Equation):
         expr = Eq(demo_v, sqrt(demo_d * demo_d1) / demo_fall.definition.t)
 
 
+def test_units_exp():
+    """Check units in exp."""
+
+    class valid_units_exp(Equation):
+        expr = Eq(demo_d/demo_d1, exp(demo_1))
+
+
+def test_units_cos():
+    """Check units in cos."""
+
+    class valid_units_exp(Equation):
+        expr = Eq(1, 1/(cos(demo_1)))
+
+
 def test_integrate():
     """Test that variables can be used as integration symbols."""
     from sympy import integrate