From: wolf Date: Tue, 16 Oct 2001 12:46:22 +0000 (+0000) Subject: Add gradient of Cinfty cutoff function. Reindent slightly. Add TODO. X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5c9cf9732b5f837a790b2f5d3bc61c47986d9679;p=dealii-svn.git Add gradient of Cinfty cutoff function. Reindent slightly. Add TODO. git-svn-id: https://svn.dealii.org/trunk@5150 0785d39b-7218-0410-832d-ea1e28bc413d --- diff --git a/deal.II/base/include/base/function_lib.h b/deal.II/base/include/base/function_lib.h index 941e52b523..0cd930c318 100644 --- a/deal.II/base/include/base/function_lib.h +++ b/deal.II/base/include/base/function_lib.h @@ -877,7 +877,8 @@ namespace Functions /** * Cut-off function for an arbitrary ball. This is the traditional * cut-off function in C-infinity for a ball of certain @p{radius} - * around @p{center}. + * around @p{center}, $f(r)=exp(1-1/(1-r**2/s**2))$, where $r$ is the + * distance to the center, and $s$ is the radius of the sphere. * * @author Guido Kanschat, 2001 */ @@ -906,6 +907,12 @@ namespace Functions std::vector &values, const unsigned int component = 0) const; + /** + * Function gradient at one point. + */ + virtual Tensor<1,dim> gradient (const Point &p, + const unsigned int component = 0) const; + private: /** * Center of the integration ball. diff --git a/deal.II/base/source/function_lib_cutoff.cc b/deal.II/base/source/function_lib_cutoff.cc index 7712347050..e5a2b3ab12 100644 --- a/deal.II/base/source/function_lib_cutoff.cc +++ b/deal.II/base/source/function_lib_cutoff.cc @@ -21,6 +21,7 @@ // in strict ANSI C mode, the following constants are not defined by // default, so we do it ourselves +//TODO:[?] Unify the various places where PI is defined to a central instance #ifndef M_PI # define M_PI 3.14159265358979323846 #endif @@ -41,9 +42,10 @@ namespace Functions template CutOffFunctionLinfty::CutOffFunctionLinfty (const double r, const Point p) - : Function (1), - center(p), - radius(r) + : + Function (1), + center(p), + radius(r) {} @@ -74,16 +76,17 @@ namespace Functions template CutOffFunctionW1::CutOffFunctionW1 (const double r, const Point p) - : Function (1), - center(p), - radius(r) + : + Function (1), + center(p), + radius(r) {} template double CutOffFunctionW1::value (const Point &p, - const unsigned int) const + const unsigned int) const { const double d = center.distance(p); return ((d CutOffFunctionCinfty::CutOffFunctionCinfty (const double r, const Point p) - : Function (1), - center(p), - radius(r) + : + Function (1), + center(p), + radius(r) {} template double CutOffFunctionCinfty::value (const Point &p, - const unsigned int) const + const unsigned int) const { const double d = center.distance(p); const double r = radius; @@ -156,6 +160,24 @@ namespace Functions } + + template + Tensor<1,dim> + CutOffFunctionCinfty::gradient (const Point &p, + const unsigned int) const + { + const double d = center.distance(p); + const double r = radius; + if (d>=r) + return Tensor<1,dim>(); + const double e = -d*d/(r-d)/(r+d); + return ((e<-50) ? + Point() : + (p-center)/d*(-2.0*r*r/pow(-r*r+d*d,2.0)*d*exp(e))); + } + + +// explicit instantiations template class CutOffFunctionLinfty <1>; template class CutOffFunctionLinfty <2>; template class CutOffFunctionLinfty <3>; @@ -167,6 +189,4 @@ namespace Functions template class CutOffFunctionCinfty <1>; template class CutOffFunctionCinfty <2>; template class CutOffFunctionCinfty <3>; - - }