Changes in src/sas/sasgui/perspectives/fitting/media/plugin.rst [ca1eaeb:20cfa23] in sasview
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src/sas/sasgui/perspectives/fitting/media/plugin.rst
rca1eaeb r20cfa23 560 560 561 561 M_PI_180, M_4PI_3: 562 $\ frac{\pi}{180}$, $\frac{4\pi}{3}$562 $\pi/{180}$, $\tfrac{4}{3}\pi$ 563 563 SINCOS(x, s, c): 564 564 Macro which sets s=sin(x) and c=cos(x). The variables *c* and *s* … … 596 596 These functions have been tuned to be fast and numerically stable down 597 597 to $q=0$ even in single precision. In some cases they work around bugs 598 which appear on some platforms but not others, so use them where needed. 599 Add the files listed in :code:`source = ["lib/file.c", ...]` to your *model.py* 600 file in the order given, otherwise these functions will not be available. 598 which appear on some platforms but not others. So use them where needed!!! 601 599 602 600 polevl(x, c, n): 603 Polynomial evaluation $p(x) = \sum_{i=0}^n c_i x^ i$ using Horner's601 Polynomial evaluation $p(x) = \sum_{i=0}^n c_i x^{n-i}$ using Horner's 604 602 method so it is faster and more accurate. 605 603 606 $c = \{c_n, c_{n-1}, \ldots, c_0 \}$ is the table of coefficients,607 sorted from highest to lowest.608 609 :code:`source = ["lib/polevl.c", ...]` (`link to code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/polevl.c>`_)610 611 p1evl(x, c, n):612 Evaluation of normalized polynomial $p(x) = x^n + \sum_{i=0}^{n-1} c_i x^i$613 using Horner's method so it is faster and more accurate.614 615 $c = \{c_{n-1}, c_{n-2} \ldots, c_0 \}$ is the table of coefficients,616 sorted from highest to lowest.617 618 604 :code:`source = ["lib/polevl.c", ...]` 619 (`link to code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/polevl.c>`_) 620 621 sas_gamma(x): 622 Gamma function $\text{sas_gamma}(x) = \Gamma(x)$. 623 624 The standard math function, tgamma(x) is unstable for $x < 1$ 605 606 sas_gamma: 607 Gamma function $\text{sas_gamma}(x) = \Gamma(x)$. The standard math 608 library gamma function, tgamma(x) is unstable below 1 on some platforms. 609 610 :code:`source = ["lib/sasgamma.c", ...]` 611 612 erf, erfc: 613 Error function 614 $\text{erf}(x) = \frac{1}{\sqrt\pi}\int_0^x e^{-t^2}\,dt$ 615 and complementary error function 616 $\text{erfc}(x) = \frac{1}{\sqrt\pi}\int_x^\inf e^{-t^2}\,dt$. 617 The standard math library erf and erfc are slower and broken 625 618 on some platforms. 626 619 627 :code:`source = ["lib/sasgamma.c", ...]`628 (`link to code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_gamma.c>`_)629 630 sas_erf(x), sas_erfc(x):631 Error function632 $\text{sas_erf}(x) = \frac{2}{\sqrt\pi}\int_0^x e^{-t^2}\,dt$633 and complementary error function634 $\text{sas_erfc}(x) = \frac{2}{\sqrt\pi}\int_x^{\infty} e^{-t^2}\,dt$.635 636 The standard math functions erf(x) and erfc(x) are slower and broken637 on some platforms.638 639 620 :code:`source = ["lib/polevl.c", "lib/sas_erf.c", ...]` 640 (`link to error functions' code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_erf.c>`_) 641 642 sas_J0(x): 643 Bessel function of the first kind $\text{sas_J0}(x)=J_0(x)$ where 621 622 sas_J0: 623 Bessel function of the first kind where 644 624 $J_0(x) = \frac{1}{\pi}\int_0^\pi \cos(x\sin(\tau))\,d\tau$. 645 625 646 The standard math function j0(x) is not available on all platforms.647 648 626 :code:`source = ["lib/polevl.c", "lib/sas_J0.c", ...]` 649 (`link to Bessel function's code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_J0.c>`_) 650 651 sas_J1(x): 652 Bessel function of the first kind $\text{sas_J1}(x)=J_1(x)$ where 627 628 sas_J1: 629 Bessel function of the first kind where 653 630 $J_1(x) = \frac{1}{\pi}\int_0^\pi \cos(\tau - x\sin(\tau))\,d\tau$. 654 631 655 The standard math function j1(x) is not available on all platforms.656 657 632 :code:`source = ["lib/polevl.c", "lib/sas_J1.c", ...]` 658 (`link to Bessel function's code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_J1.c>`_) 659 660 sas_JN(n, x): 661 Bessel function of the first kind and integer order $n$: 662 $\text{sas_JN}(n, x)=J_n(x)$ where 633 634 sas_JN: 635 Bessel function of the first kind where 663 636 $J_n(x) = \frac{1}{\pi}\int_0^\pi \cos(n\tau - x\sin(\tau))\,d\tau$. 664 If $n$ = 0 or 1, it uses sas_J0(x) or sas_J1(x), respectively.665 666 The standard math function jn(n, x) is not available on all platforms.667 637 668 638 :code:`source = ["lib/polevl.c", "lib/sas_J0.c", "lib/sas_J1.c", "lib/sas_JN.c", ...]` 669 (`link to Bessel function's code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_JN.c>`_) 670 671 Si(x): 639 640 Si: 672 641 Sine integral $\text{Si}(x) = \int_0^x \tfrac{\sin t}{t}\,dt$. 673 642 674 This function uses Taylor series for small and large arguments: 675 676 For large arguments, 677 678 .. math:: 679 680 \text{Si}(x) \sim \frac{\pi}{2} 681 - \frac{\cos(x)}{x}\left(1 - \frac{2!}{x^2} + \frac{4!}{x^4} - \frac{6!}{x^6} \right) 682 - \frac{\sin(x)}{x}\left(\frac{1}{x} - \frac{3!}{x^3} + \frac{5!}{x^5} - \frac{7!}{x^7}\right) 683 684 For small arguments, 685 686 .. math:: 687 688 \text{Si}(x) \sim x 689 - \frac{x^3}{3\times 3!} + \frac{x^5}{5 \times 5!} - \frac{x^7}{7 \times 7!} 690 + \frac{x^9}{9\times 9!} - \frac{x^{11}}{11\times 11!} 691 692 :code:`source = ["lib/Si.c", ...]` 693 (`link to code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/Si.c>`_) 694 695 sph_j1c(x): 643 :code:`soure = ["lib/Si.c", ...]` 644 645 sph_j1c(qr): 696 646 Spherical Bessel form 697 $\text{sph_j1c}(x) = 3 j_1(x)/x = 3 (\sin(x) - x \cos(x))/x^3$, 698 with a limiting value of 1 at $x=0$, where $j_1(x)$ is the spherical 699 Bessel function of the first kind and first order. 700 701 This function uses a Taylor series for small $x$ for numerical accuracy. 647 $F(qr) = 3 j_1(qr)/(qr) = 3 (\sin(qr) - qr \cos(qr))/{(qr)^3}$, 648 with a limiting value of 1 at $qr=0$. This function uses a Taylor 649 series for small $qr$ for numerical accuracy. 702 650 703 651 :code:`source = ["lib/sph_j1c.c", ...]` 704 (`link to code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sph_j1c.c>`_) 705 706 707 sas_J1c(x): 708 Bessel form $\text{sas_J1c}(x) = 2 J_1(x)/x$, with a limiting value 709 of 1 at $x=0$, where $J_1(x)$ is the Bessel function of first kind 710 and first order. 652 653 sas_J1c(qr): 654 Bessel form $F(qr) = 2 J_1(qr)/{(qr)}$, with a limiting value of 1 at $qr=0$. 711 655 712 656 :code:`source = ["lib/polevl.c", "lib/sas_J1.c", ...]` 713 (`link to Bessel form's code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/sas_J1.c>`_) 714 715 716 Gauss76Z[i], Gauss76Wt[i]: 717 Points $z_i$ and weights $w_i$ for 76-point Gaussian quadrature, respectively, 718 computing $\int_{-1}^1 f(z)\,dz \approx \sum_{i=1}^{76} w_i\,f(z_i)$. 719 720 Similar arrays are available in :code:`gauss20.c` for 20-point 721 quadrature and in :code:`gauss150.c` for 150-point quadrature. 722 723 :code:`source = ["lib/gauss76.c", ...]` 724 (`link to code <https://github.com/SasView/sasmodels/tree/master/sasmodels/models/lib/gauss76.c>`_) 725 726 657 658 Gauss76z[i], Gauss76Wt[i]: 659 Points $z_i$ and weights $w_i$ for 76-point Gaussian quadrature, 660 computing $\int_{-1}^1 f(z)\,dz \approx \sum_{i=1}^{76} w_i f(z_i)$. 661 Similar arrays are available in :code:`gauss20.c` for 20 point 662 quadrature and in :code:`gauss150.c` for 150 point quadrature. 663 664 :code:`source = ["gauss76.c", ...]` 727 665 728 666 Problems with C models
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