@@ -208,25 +208,29 @@ class LaplacianThicknessInputSpec(ANTSCommandInputSpec):
 keep_extension=True,
 hash_files=False)
 smooth_param = traits.Float(
-argstr='%f',
+argstr='%s',
 desc='Sigma of the Laplacian Recursive Image Filter (defaults to 1)',
 position=4)
 prior_thickness = traits.Float(
-argstr='%f',
+argstr='%s',
 desc='Prior thickness (defaults to 500)',
+requires=['smooth_param'],
 position=5)
 dT = traits.Float(
-argstr='%f',
+argstr='%s',
 desc='Time delta used during integration (defaults to 0.01)',
+requires=['prior_thickness'],
 position=6)
 sulcus_prior = traits.Float(
-argstr='%f',
+argstr='%s',
 desc='Positive floating point number for sulcus prior. '
 'Authors said that 0.15 might be a reasonable value',
+requires=['dT'],
 position=7)
 tolerance = traits.Float(
-argstr='%f',
+argstr='%s',
 desc='Tolerance to reach during optimization (defaults to 0.001)',
+requires=['sulcus_prior'],
 position=8)
 
 

@@ -7,8 +7,9 @@ def test_LaplacianThickness_inputs():
 input_map = dict(
 args=dict(argstr='%s', ),
 dT=dict(
-argstr='%f',
+argstr='%s',
 position=6,
+requires=['prior_thickness'],
 ),
 environ=dict(
 nohash=True,
@@ -39,20 +40,23 @@ def test_LaplacianThickness_inputs():
 position=3,
 ),
 prior_thickness=dict(
-argstr='%f',
+argstr='%s',
 position=5,
+requires=['smooth_param'],
 ),
 smooth_param=dict(
-argstr='%f',
+argstr='%s',
 position=4,
 ),
 sulcus_prior=dict(
-argstr='%f',
+argstr='%s',
 position=7,
+requires=['dT'],
 ),
 tolerance=dict(
-argstr='%f',
+argstr='%s',
 position=8,
+requires=['sulcus_prior'],
 ),
 )
 inputs = LaplacianThickness.input_spec()

@@ -202,10 +202,16 @@ def _check_requires(self, spec, name, value):
 for field in spec.requires
 ]
 if any(values) and isdefined(value):
-msg = ("%s requires a value for input '%s' because one of %s "
-"is set. For a list of required inputs, see %s.help()" %
-(self.__class__.__name__, name,
-', '.join(spec.requires), self.__class__.__name__))
+if len(values) > 1:
+fmt = ("%s requires values for inputs %s because '%s' is set. "
+"For a list of required inputs, see %s.help()")
+else:
+fmt = ("%s requires a value for input %s because '%s' is set. "
+"For a list of required inputs, see %s.help()")
+msg = fmt % (self.__class__.__name__,
+', '.join("'%s'" % req for req in spec.requires),
+name,
+self.__class__.__name__)
 raise ValueError(msg)
 
 def _check_xor(self, spec, name, value):