* Imported more recent function fitting facility from Cr2 project.

math/fitting/funcs_physics.py

@@ -0,0 +1,49 @@
+#
+# wpylib.math.fitting.funcs_physics module
+# Created: 20150521
+# Wirawan Purwanto
+#
+# Imported 20150521 from Cr2_analysis_cbs.py
+# (dated 20141017, CVS rev 1.143).
+#
+
+"""
+wpylib.math.fitting.funcs_physics module
+A library of simple f(x) functions for physics-related common functional fitting
+
+For use with OO-style x-y curve fitting interface.
+"""
+
+import numpy
+
+
+class FermiDirac_fit_func(fit_func_base):
+  """Fermi-Dirac function object.
+  For use with fit_func function.
+
+  Functional form:
+
+      C[0] * (exp((x - C[1]) / C[2]) + 1)^-1
+
+  Coefficients:
+  * C[0] = amplitude
+  * C[1] = transition "temperature"
+  * C[2] = "smearing temperature"
+  """
+  dim = 1  # a function with 1-D domain
+  param_names = ('A', 'F', 'T')
+  # FIXME: Not good yet!!!
+  F_guess = 1.9
+  T_guess = 0.05
+  def __call__(self, C, x):
+    from numpy import exp
+    A, F, T = self.get_params(C, *(self.param_names))
+    y = A * (exp((x[0] - F) / T) + 1)**(-1)
+    self.func_call_hook(C, x, y)
+    return y
+  def Guess_xy(self, x, y):
+    imin = numpy.argmin(y)
+    self.guess_params = (y[imin], self.F_guess, self.T_guess)
+    return self.guess_params
+
+