Changes in sasmodels/sesans.py [94d13f1:2cdc35b] in sasmodels

File:

• sasmodels/sesans.py (modified) (3 diffs)

sasmodels/sesans.py

@@ -20 +20 @@
     Spin-Echo SANS transform calculator.  Similar to a resolution function,
     the SesansTransform object takes I(q) for the set of *q_calc* values and
-    produces a transformed dataset
+    produces a transformed dataset.
 
     *SElength* (A) is the set of spin-echo lengths in the measured data.
@@ -48 +48 @@
 
     def apply(self, Iq):
-        # tye: (np.ndarray) -> np.ndarray
         G0 = np.dot(self._H0, Iq)
         G = np.dot(self._H.T, Iq)
@@ -73 +72 @@
         self.q_calc = q
         self._H, self._H0 = H, H0
+
+class OrientedSesansTransform(object):
+    """
+    Oriented Spin-Echo SANS transform calculator.  Similar to a resolution
+    function, the OrientedSesansTransform object takes I(q) for the set
+    of *q_calc* values and produces a transformed dataset.
+
+    *SElength* (A) is the set of spin-echo lengths in the measured data.
+
+    *zaccept* (1/A) is the maximum acceptance of scattering vector in the spin
+    echo encoding dimension (for ToF: Q of min(R) and max(lam)).
+
+    *Rmax* (A) is the maximum size sensitivity; larger radius requires more
+    computation time.
+    """
+    #: SElength from the data in the original data units; not used by transform
+    #: but the GUI uses it, so make sure that it is present.
+    q = None  # type: np.ndarray
+
+    #: q values to calculate when computing transform
+    q_calc = None  # type: np.ndarray
+
+    # transform arrays
+    _cosmat = None  # type: np.ndarray
+    _cos0 = None # type: np.ndarray
+    _Iq_shape = None # type: Tuple[int, int]
+
+    def __init__(self, z, SElength, zaccept, Rmax):
+        # type: (np.ndarray, float, float) -> None
+        #import logging; logging.info("creating SESANS transform")
+        self.q = z
+        self._set_cosmat(SElength, zaccept, Rmax)
+
+    def apply(self, Iq):
+        dq = self.q_calc[0][0]
+        Iq = np.reshape(Iq, self._Iq_shape)
+        G0 = self._cos0 * np.sum(Iq) * dq
+        G = np.sum(np.dot(Iq, self._cosmat), axis=0) * dq
+        P = G - G0
+        return P
+
+    def _set_cosmat(self, SElength, zaccept, Rmax):
+        # type: (np.ndarray, float, float) -> None
+        # Force float32 arrays, otherwise run into memory problems on some machines
+        SElength = np.asarray(SElength, dtype='float32')
+
+        # Rmax = #value in text box somewhere in FitPage?
+        q_max = 2 * pi / (SElength[1] - SElength[0])
+        q_min = 0.1 * 2 * pi / (np.size(SElength) * SElength[-1])
+        q_min *= 100
+
+        q = np.arange(q_min, q_max, q_min, dtype='float32')
+        dq = q_min
+
+        cos0 = np.float32(dq / (2 * pi))
+        cosmat = np.float32(dq / (2 * pi)) * np.cos(q[:, None] * SElength[None, :])
+
+        qx, qy = np.meshgrid(q, q)
+        self._Iq_shape = qx.shape
+        self.q_calc = qx.flatten(), qy.flatten()
+        self._cosmat, self._cos0 = cosmat, cos0