# Changeset 0a9fcab in sasmodels for sasmodels/special.py

Ignore:
Timestamp:
Dec 4, 2017 6:13:55 AM (6 years ago)
Children:
2db9fe4
Parents:
ef6a512
Message:

simplify handling of gauss.z in py2c

File:
1 edited

### Legend:

Unmodified
 ref6a512 ................. The C code follows the C99 standard, with the usual math functions, as defined in OpenCL _. This includes the following: This following standard C99 math functions are available: M_PI, M_PI_2, M_PI_4, M_SQRT1_2, M_E: $\pi$, $\pi/2$, $\pi/4$, $1/\sqrt{2}$ and Euler's constant $e$ exp, log, pow(x,y), expm1, sqrt: Power functions $e^x$, $\ln x$, $x^y$, $e^x - 1$, $\sqrt{x}$. The function expm1(x) is accurate across all $x$, including $x$ very close to zero. exp, log, pow(x,y), expm1, log1p, sqrt, cbrt: Power functions $e^x$, $\ln x$, $x^y$, $e^x - 1$, $\ln 1 + x$, $\sqrt{x}$, $\sqrt{x}$. The functions expm1(x) and log1p(x) are accurate across all $x$, including $x$ very close to zero. sin, cos, tan, asin, acos, atan: quadrants II and IV when $x$ and $y$ have opposite sign. fmin(x,y), fmax(x,y), trunc, rint: fabs(x), fmin(x,y), fmax(x,y), trunc, rint: Floating point functions.  rint(x) returns the nearest integer. NaN, Not a Number, $0/0$.  Use isnan(x) to test for NaN.  Note that you cannot use :code:x == NAN to test for NaN values since that will always return false.  NAN does not equal NAN! will always return false.  NAN does not equal NAN!  The alternative, :code:x != x may fail if the compiler optimizes the test away. INFINITY: for forcing a constant to stay double precision. The following special functions and scattering calculations are defined in sasmodels/models/lib _. The following special functions and scattering calculations are defined. These functions have been tuned to be fast and numerically stable down to $q=0$ even in single precision.  In some cases they work around bugs Gauss76Z[i], Gauss76Wt[i]: gauss76.n, gauss76.z[i], gauss76.w[i]: Points $z_i$ and weights $w_i$ for 76-point Gaussian quadrature, respectively, computing $\int_{-1}^1 f(z)\,dz \approx \sum_{i=1}^{76} w_i\,f(z_i)$. Similar arrays are available in :code:gauss20.c for 20-point quadrature and in :code:gauss150.c for 150-point quadrature. When translating the model to C, include 'lib/gauss76.c' in the source and use :code:GAUSS_N, :code:GAUSS_Z, and :code:GAUSS_W. Similar arrays are available in :code:gauss20 for 20-point quadrature and :code:gauss150.c for 150-point quadrature. By using :code:import gauss76 as gauss it is easy to change the number of points in the integration. """ # pylint: disable=unused-import # C99 standard math library functions from numpy import exp, log, power as pow, expm1, sqrt from numpy import exp, log, power as pow, expm1, logp1, sqrt, cbrt from numpy import sin, cos, tan, arcsin as asin, arccos as acos, arctan as atan from numpy import sinh, cosh, tanh, arcsinh as asinh, arccosh as acosh, arctanh as atanh from numpy import arctan2 as atan2 from numpy import fmin, fmax, trunc, rint from numpy import fabs, fmin, fmax, trunc, rint from numpy import pi, nan, inf from scipy.special import gamma as sas_gamma