parabola on a log-scale added

src/nmreval/models/basic.py

@@ -133,6 +133,30 @@ class Parabola:
         return c * (x-x0)**2 + y0
 
 
+class ParabolaLog:
+    """
+    Parabola (on a log-scale) with vertex :math:`(x_0, y_0)`
+
+    .. math::
+        y = C\cdot (x-x_{0}) + y_0
+
+    Args:
+        x (array_like): Input values
+        c (float): Slope
+        x0 (float): x position of vertex
+        y0 (float): y position of vertex
+
+    """
+    type = 'Basic'
+    name = 'Log-Parabola'
+    equation = 'exp[C*(x-x_{0})^{2} + y_{0}]'
+    params = ['C', 'x_{0}', 'y_{0}']
+
+    @staticmethod
+    def func(x, c, x0, y0):
+        return np.exp(c * (x-x0)**2 + y0)
+
+
 class PowerLawCross:
     """
     Crossover between power laws