Changes in / [b66d38e:09d7a54] in sasmodels
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sasmodels/models/_bessel.py
r275b98e5 r0f910a7 1 1 r""" 2 For information about polarised and magnetic scattering, click here_. 3 4 .. _here: polar_mag_help.html 2 This is a test function! 5 3 6 4 Definition 7 5 ---------- 8 6 9 The 1D scattering intensity is calculated in the following way (Guinier, 1955) 10 11 .. math:: 12 13 I(q) = \frac{\text{scale}}{V} \cdot \left[ 14 3V(\Delta\rho) \cdot \frac{\sin(qr) - qr\cos(qr))}{(qr)^3} 15 \right]^2 + \text{background} 16 17 where *scale* is a volume fraction, $V$ is the volume of the scatterer, 18 $r$ is the radius of the sphere, *background* is the background level and 19 *sld* and *solvent_sld* are the scattering length densities (SLDs) of the 20 scatterer and the solvent respectively. 21 22 Note that if your data is in absolute scale, the *scale* should represent 23 the volume fraction (which is unitless) if you have a good fit. If not, 24 it should represent the volume fraction times a factor (by which your data 25 might need to be rescaled). 26 27 The 2D scattering intensity is the same as above, regardless of the 28 orientation of $\vec q$. 29 30 Validation 31 ---------- 32 33 Validation of our code was done by comparing the output of the 1D model 34 to the output of the software provided by the NIST (Kline, 2006). 35 Figure :numref:`figure #sphere-comparison` shows a comparison of the output 36 of our model and the output of the NIST software. 37 38 .. _sphere-comparison: 39 40 .. figure:: img/sphere_comparison.jpg 41 42 Comparison of the DANSE scattering intensity for a sphere with the 43 output of the NIST SANS analysis software. The parameters were set to: 44 *scale* = 1.0, *radius* = 60 |Ang|, *contrast* = 1e-6 |Ang^-2|, and 45 *background* = 0.01 |cm^-1|. 46 7 Calculates a bessel function. Maybe... 47 8 48 9 References 49 10 ---------- 50 11 51 A Guinier and G. Fournet, *Small-Angle Scattering of X-Rays*, 52 John Wiley and Sons, New York, (1955) 53 54 *2013/09/09 and 2014/01/06 - Description reviewed by S King and P Parker.* 12 None 55 13 """ 56 14 … … 60 18 title = "Bessel function testing" 61 19 description = """\ 62 Lev raging current infrastracture to test Bessel function performance on20 Leveraging current infrastructure to test Bessel function performance on 63 21 """ 64 category = "special_fu cntions:bessel"22 category = "special_functions:bessel" 65 23 66 24 # ["name", "units", default, [lower, upper], "type","description"],
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