1 | r""" |
---|
2 | This model describes a Gaussian shaped peak on a flat background |
---|
3 | |
---|
4 | .. image:: img/image198.PNG |
---|
5 | |
---|
6 | with the peak having height of *I0* centered at *q0* and having a standard deviation of *B*. The FWHM (full-width |
---|
7 | half-maximum) is 2.354 B. |
---|
8 | |
---|
9 | For 2D data: The 2D scattering intensity is calculated in the same way as 1D, where the *q* vector is defined as |
---|
10 | |
---|
11 | .. image:: img/image040.gif |
---|
12 | |
---|
13 | .. image:: img/image199.jpg |
---|
14 | |
---|
15 | *Figure. 1D plot using the default values (w/500 data points).* |
---|
16 | |
---|
17 | REFERENCE |
---|
18 | --------- |
---|
19 | |
---|
20 | None. |
---|
21 | """ |
---|
22 | |
---|
23 | from numpy import inf |
---|
24 | |
---|
25 | name = "gaussian_peak" |
---|
26 | title = "Gaussian shaped peak" |
---|
27 | description = """ |
---|
28 | Model describes a Gaussian shaped peak including a flat background |
---|
29 | Provide F(q) = scale*exp( -1/2 *[(q-q0)/B]^2 )+ background |
---|
30 | """ |
---|
31 | category = "shape-independent" |
---|
32 | |
---|
33 | # ["name", "units", default, [lower, upper], "type","description"], |
---|
34 | parameters = [["q0", "1/Ang", 0.05, [-inf, inf], "", "Peak position"], |
---|
35 | ["sigma", "1/Ang", 0.005, [-inf, inf], "", |
---|
36 | "Peak width (standard deviation)"], |
---|
37 | ] |
---|
38 | |
---|
39 | # No volume normalization despite having a volume parameter |
---|
40 | # This should perhaps be volume normalized? |
---|
41 | form_volume = """ |
---|
42 | return 1.0; |
---|
43 | """ |
---|
44 | |
---|
45 | Iq = """ |
---|
46 | return exp(-0.5*pow((q - q0)/sigma,2.0)); |
---|
47 | """ |
---|
48 | |
---|
49 | |
---|
50 | Iqxy = """ |
---|
51 | // never called since no orientation or magnetic parameters. |
---|
52 | //return -1.0; |
---|
53 | return Iq(sqrt(qx*qx + qy*qy), q0, sigma); |
---|
54 | """ |
---|
55 | |
---|
56 | |
---|
57 | # VR defaults to 1.0 |
---|
58 | |
---|
59 | demo = dict(scale=1, background=0, q0=0.05, sigma=0.005) |
---|
60 | oldname = "PeakGaussModel" |
---|
61 | oldpars = dict(sigma='B') |
---|