[d1fe925] | 1 | r""" |
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| 2 | This model describes a Gaussian shaped peak on a flat background |
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| 3 | |
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| 4 | .. image:: img/image198.PNG |
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| 5 | |
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| 6 | with the peak having height of *I0* centered at *q0* and having a standard deviation of *B*. The FWHM (full-width |
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| 7 | half-maximum) is 2.354 B. |
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| 8 | |
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| 9 | For 2D data: The 2D scattering intensity is calculated in the same way as 1D, where the *q* vector is defined as |
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| 10 | |
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| 11 | .. image:: img/image040.gif |
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| 12 | |
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| 13 | .. image:: img/image199.jpg |
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| 14 | |
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| 15 | *Figure. 1D plot using the default values (w/500 data points).* |
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| 16 | |
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| 17 | REFERENCE |
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| 18 | --------- |
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| 19 | |
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| 20 | None. |
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| 21 | """ |
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| 22 | |
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| 23 | from numpy import inf |
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| 24 | |
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| 25 | name = "gaussian_peak" |
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| 26 | title = "Gaussian shaped peak" |
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| 27 | description = """ |
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| 28 | Model describes a Gaussian shaped peak including a flat background |
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| 29 | Provide F(q) = scale*exp( -1/2 *[(q-q0)/B]^2 )+ background |
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| 30 | """ |
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| 31 | category = "shape-independent" |
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| 32 | |
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| 33 | # ["name", "units", default, [lower, upper], "type","description"], |
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| 34 | parameters = [["q0", "1/Ang", 0.05, [-inf, inf], "", "Peak position"], |
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| 35 | ["sigma", "1/Ang", 0.005, [-inf, inf], "", |
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| 36 | "Peak width (standard deviation)"], |
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| 37 | ] |
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| 38 | |
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| 39 | # No volume normalization despite having a volume parameter |
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| 40 | # This should perhaps be volume normalized? |
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| 41 | form_volume = """ |
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| 42 | return 1.0; |
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| 43 | """ |
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| 44 | |
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| 45 | Iq = """ |
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| 46 | return exp(-0.5*pow((q - q0)/sigma,2.0)); |
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| 47 | """ |
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| 48 | |
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| 49 | |
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| 50 | Iqxy = """ |
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| 51 | // never called since no orientation or magnetic parameters. |
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| 52 | //return -1.0; |
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| 53 | return Iq(sqrt(qx*qx + qy*qy), q0, sigma); |
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| 54 | """ |
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| 55 | |
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| 56 | |
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| 57 | # VR defaults to 1.0 |
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| 58 | |
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| 59 | demo = dict(scale=1, background=0, q0=0.05, sigma=0.005) |
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| 60 | oldname = "PeakGaussModel" |
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| 61 | oldpars = dict(sigma='B') |
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