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allow any number of rings in sharp_make_ecp_geom_info()

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This commit is contained in:
Martin Reinecke 2012-11-23 13:28:51 +01:00
parent 7d23ebcc39
commit 94c6a99ad8
2 changed files with 17 additions and 35 deletions
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49
libsharp/sharp_geomhelpers.c
View file

@ -158,21 +158,6 @@ static void gauss_legendre_tbl(int n, double* x, double* w)
}
}
static void makeweights (int bw, double *weights)
{
const double pi = 3.141592653589793238462643383279502884197;
const double fudge = pi/(4*bw);
for (int j=0; j<2*bw; ++j)
{
double tmpsum = 0;
for (int k=0; k<bw; ++k)
tmpsum += 1./(2*k+1) * sin((2*j+1)*(2*k+1)*fudge);
tmpsum *= sin((2*j+1)*fudge);
tmpsum *= 2./bw;
weights[j] = tmpsum;
}
}
void sharp_make_gauss_geom_info (int nrings, int nphi, double phi0,
int stride_lon, int stride_lat, sharp_geom_info **geom_info)
{
@ -207,7 +192,8 @@ void sharp_make_gauss_geom_info (int nrings, int nphi, double phi0,
DEALLOC(stride_);
}
void sharp_make_ecp_geom_info (int nrings, int nphi, double phi0,
/* Weights from Waldvogel 2006: BIT Numerical Mathematics 46, p. 195 */
void sharp_make_ecp_geom_info (int nrings, int ppring, double phi0,
int stride_lon, int stride_lat, sharp_geom_info **geom_info)
{
const double pi=3.141592653589793238462643383279502884197;
@ -219,17 +205,21 @@ void sharp_make_ecp_geom_info (int nrings, int nphi, double phi0,
ptrdiff_t *ofs=RALLOC(ptrdiff_t,nrings);
int *stride_=RALLOC(int,nrings);
UTIL_ASSERT((nrings&1)==0,
"Even number of rings needed for equidistant grid!");
makeweights(nrings/2,weight);
for (int m=0; m<nrings; ++m)
for (int m=0; m<(nrings+1)/2; ++m)
{
theta[m] = (m+0.5)*pi/nrings;
nph[m]=nphi;
phi0_[m]=phi0;
theta[m]=pi*(m+0.5)/nrings;
theta[nrings-1-m]=pi-theta[m];
nph[m]=nph[nrings-1-m]=ppring;
phi0_[m]=phi0_[nrings-1-m]=phi0;
ofs[m]=(ptrdiff_t)m*stride_lat;
stride_[m]=stride_lon;
weight[m]*=2*pi/nphi;
ofs[nrings-1-m]=(ptrdiff_t)((nrings-1-m)*stride_lat);
stride_[m]=stride_[nrings-1-m]=stride_lon;
double wgt=0;
int n=nrings;
for (int j=1; j<=n/2; ++j)
wgt += cos(((j*(2*m+1))%(2*n))*(pi/nrings))/(4.*j*j-1.);
wgt = 2./n*(1.-2*wgt)*2*pi/nph[m];
weight[m]=weight[nrings-1-m]=wgt;
}
sharp_make_geom_info (nrings, nph, ofs, stride_, phi0_, theta, NULL, weight,
@ -243,13 +233,6 @@ void sharp_make_ecp_geom_info (int nrings, int nphi, double phi0,
DEALLOC(stride_);
}
static inline double eps(int j, int J)
{
if ((j==0)||(j==J)) return 0.5;
if ((j>0)&&(j<J)) return 1.;
return 0.;
}
/* Weights from Waldvogel 2006: BIT Numerical Mathematics 46, p. 195 */
void sharp_make_hw_geom_info (int nrings, int ppring, double phi0,
int stride_lon, int stride_lat, sharp_geom_info **geom_info)
@ -263,7 +246,7 @@ void sharp_make_hw_geom_info (int nrings, int ppring, double phi0,
ptrdiff_t *ofs=RALLOC(ptrdiff_t,nrings);
int *stride_=RALLOC(int,nrings);
for (int m=0; m<=nrings/2; ++m)
for (int m=0; m<(nrings+1)/2; ++m)
{
theta[m]=pi*m/(nrings-1.);
if (theta[m]<1e-15) theta[m]=1e-15;

3
libsharp/sharp_geomhelpers.h
View file

@ -25,7 +25,7 @@
/*! \file sharp_geomhelpers.h
* SHARP helper function for the creation of grid geometries
*
* Copyright (C) 2006-2011 Max-Planck-Society
* Copyright (C) 2006-2012 Max-Planck-Society
* \author Martin Reinecke
*/
@ -69,7 +69,6 @@ void sharp_make_gauss_geom_info (int nrings, int nphi, double phi0,
is \a stride_lat.
\note The spacing of pixel centers is equidistant in colatitude and
longitude.
\note \a nrings must be an even number.
\note The sphere is pixelized in a way that the colatitude of the first ring
is \a 0.5*(pi/nrings) and the colatitude of the last ring is
\a pi-0.5*(pi/nrings). There are no pixel centers at the poles.