Changeset aa8c6e0 in sasmodels for doc/guide/plugin.rst
- Timestamp:
- Oct 30, 2018 8:43:35 AM (5 years ago)
- Branches:
- master, core_shell_microgels, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests
- Children:
- 765d025, 23df833
- Parents:
- 153f8f6 (diff), c6084f1 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent. - File:
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- 1 edited
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doc/guide/plugin.rst
r81751c2 raa8c6e0 744 744 erf, erfc, tgamma, lgamma: **do not use** 745 745 Special functions that should be part of the standard, but are missing 746 or inaccurate on some platforms. Use sas_erf, sas_erfc andsas_gamma747 instead (see below). Note: lgamma(x) has not yet been tested.746 or inaccurate on some platforms. Use sas_erf, sas_erfc, sas_gamma 747 and sas_lgamma instead (see below). 748 748 749 749 Some non-standard constants and functions are also provided: … … 812 812 Gamma function sas_gamma\ $(x) = \Gamma(x)$. 813 813 814 The standard math function, tgamma(x) is unstable for $x < 1$814 The standard math function, tgamma(x), is unstable for $x < 1$ 815 815 on some platforms. 816 816 817 817 :code:`source = ["lib/sas_gamma.c", ...]` 818 818 (`sas_gamma.c <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_gamma.c>`_) 819 820 sas_gammaln(x): 821 log gamma function sas_gammaln\ $(x) = \log \Gamma(|x|)$. 822 823 The standard math function, lgamma(x), is incorrect for single 824 precision on some platforms. 825 826 :code:`source = ["lib/sas_gammainc.c", ...]` 827 (`sas_gammainc.c <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_gammainc.c>`_) 828 829 sas_gammainc(a, x), sas_gammaincc(a, x): 830 Incomplete gamma function 831 sas_gammainc\ $(a, x) = \int_0^x t^{a-1}e^{-t}\,dt / \Gamma(a)$ 832 and complementary incomplete gamma function 833 sas_gammaincc\ $(a, x) = \int_x^\infty t^{a-1}e^{-t}\,dt / \Gamma(a)$ 834 835 :code:`source = ["lib/sas_gammainc.c", ...]` 836 (`sas_gammainc.c <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_gammainc.c>`_) 819 837 820 838 sas_erf(x), sas_erfc(x): … … 854 872 If $n$ = 0 or 1, it uses sas_J0($x$) or sas_J1($x$), respectively. 855 873 874 Warning: JN(n,x) can be very inaccurate (0.1%) for x not in [0.1, 100]. 875 856 876 The standard math function jn(n, x) is not available on all platforms. 857 877 … … 862 882 Sine integral Si\ $(x) = \int_0^x \tfrac{\sin t}{t}\,dt$. 863 883 884 Warning: Si(x) can be very inaccurate (0.1%) for x in [0.1, 100]. 885 864 886 This function uses Taylor series for small and large arguments: 865 887 866 For large arguments ,888 For large arguments use the following Taylor series, 867 889 868 890 .. math:: … … 872 894 - \frac{\sin(x)}{x}\left(\frac{1}{x} - \frac{3!}{x^3} + \frac{5!}{x^5} - \frac{7!}{x^7}\right) 873 895 874 For small arguments ,896 For small arguments , 875 897 876 898 .. math::
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