Fixed the float not subscriptable error

Author: Unique-Usman

utilities/data_simulation/GenerateData.py

@@ -75,7 +75,7 @@ def multiexponential_signal(self, D, F, S0, bvalues):
         assert len(D) == len(F), 'D and F must be the same length'
         signal = self._op.zeros_like(bvalues)
         for [d, f] in zip(D, F):
-            signal += f * self.exponential_signal(d[0], bvalues)
+            signal += f * self.exponential_signal(d, bvalues)
         signal *= S0
         return signal