Changes in sasmodels/weights.py [2d81cfe:3d58247] in sasmodels

File:

• sasmodels/weights.py (modified) (4 diffs)

sasmodels/weights.py

@@ -97 +97 @@
         return x, px
 
+class UniformDispersion(Dispersion):
+    r"""
+    Uniform dispersion, with width $\sigma$.
+
+    .. math::
+
+        w = 1
+    """
+    type = "uniform"
+    default = dict(npts=35, width=0, nsigmas=None)
+    def _weights(self, center, sigma, lb, ub):
+        x = np.linspace(center-sigma, center+sigma, self.npts)
+        x = x[(x >= lb) & (x <= ub)]
+        return x, np.ones_like(x)
 
 class RectangleDispersion(Dispersion):
@@ -107 +121 @@
     """
     type = "rectangle"
-    default = dict(npts=35, width=0, nsigmas=1.70325)
-    def _weights(self, center, sigma, lb, ub):
-        x = self._linspace(center, sigma, lb, ub)
-        x = x[np.fabs(x-center) <= np.fabs(sigma)*sqrt(3.0)]
-        return x, np.ones_like(x)
-
+    default = dict(npts=35, width=0, nsigmas=1.73205)
+    def _weights(self, center, sigma, lb, ub):
+         x = self._linspace(center, sigma, lb, ub)
+         x = x[np.fabs(x-center) <= np.fabs(sigma)*sqrt(3.0)]
+         return x, np.ones_like(x)
 
 class LogNormalDispersion(Dispersion):
@@ -190 +203 @@
         return x, px
 
+class BoltzmannDispersion(Dispersion):
+    r"""
+    Boltzmann dispersion, with $\sigma=k T/E$.
+
+    .. math::
+
+        w = \exp\left( -|x - c|/\sigma\right)
+    """
+    type = "boltzmann"
+    default = dict(npts=35, width=0, nsigmas=3)
+    def _weights(self, center, sigma, lb, ub):
+        x = self._linspace(center, sigma, lb, ub)
+        px = np.exp(-np.abs(x-center) / np.abs(sigma))
+        return x, px
 
 # dispersion name -> disperser lookup table.
@@ -196 +223 @@
 MODELS = OrderedDict((d.type, d) for d in (
     RectangleDispersion,
+    UniformDispersion,
     ArrayDispersion,
     LogNormalDispersion,
     GaussianDispersion,
     SchulzDispersion,
+    BoltzmannDispersion
 ))