Changes in / [6ad0e87:4416868] in sasmodels


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sasmodels/models
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  • sasmodels/models/guinier.py

    ra84a0ca r45330ed  
    55This model fits the Guinier function 
    66 
    7 .. math:: q_1=\frac{1}{R_g}\sqrt{\frac{(m-s)(3-s)}{2}} 
     7.. math:: I(q) = scale \exp{\left[ \frac{-Q^2R_g^2}{3} \right]} 
    88 
    99to the data directly without any need for linearisation 
    10 (*cf*. $\ln I(q)$ vs $q^2$\ ). 
     10(*cf*. the usual plot of $\ln I(q)$ vs $q^2$\ ). Note that you may have to  
     11restrict the data range to include small q only, where the Guinier approximation 
     12actually applies. See also the guinier_porod model. 
    1113 
    1214For 2D data the scattering intensity is calculated in the same way as 1D, 
     
    2729title = "" 
    2830description = """ 
    29  I(q) = scale exp ( - rg^2 q^2 / 3.0 ) 
     31 I(q) = scale.exp ( - rg^2 q^2 / 3.0 ) 
    3032  
    3133    List of default parameters: 
  • sasmodels/models/guinier_porod.py

    raa2edb2 r45330ed  
    3939Note that the radius-of-gyration for a sphere of radius R is given by $R_g = R \sqrt(3/5)$. 
    4040 
    41 The cross-sectional radius-of-gyration for a randomly oriented cylinder 
    42 of radius R is given by $R_g = R / \sqrt(2)$. 
     41For a cylinder of radius $R$ and length $L$,    $R_g^2 = \frac{L^2}{12} + \frac{R^2}{2}$ 
    4342 
    44 The cross-sectional radius-of-gyration of a randomly oriented lamella 
     43from which the cross-sectional radius-of-gyration for a randomly oriented thin  
     44cylinder is $R_g = R / \sqrt(2)$. 
     45 
     46and the cross-sectional radius-of-gyration of a randomly oriented lamella 
    4547of thickness $T$ is given by $R_g = T / \sqrt(12)$. 
    4648 
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