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add support for a Fejer 2 type grid

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This commit is contained in:
Martin Reinecke 2012-11-27 16:32:34 +01:00
parent ccf358f9d4
commit a9bc412c7f
2 changed files with 62 additions and 0 deletions
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47
libsharp/sharp_geomhelpers.c
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@ -289,6 +289,53 @@ void sharp_make_hw_geom_info (int nrings, int ppring, double phi0,
DEALLOC(stride_);
}
/* Weights from Waldvogel 2006: BIT Numerical Mathematics 46, p. 195 */
void sharp_make_fejer2_geom_info (int nrings, int ppring, double phi0,
int stride_lon, int stride_lat, sharp_geom_info **geom_info)
{
const double pi=3.141592653589793238462643383279502884197;
double *theta=RALLOC(double,nrings);
double *weight=RALLOC(double,nrings+1);
int *nph=RALLOC(int,nrings);
double *phi0_=RALLOC(double,nrings);
ptrdiff_t *ofs=RALLOC(ptrdiff_t,nrings);
int *stride_=RALLOC(int,nrings);
int n=nrings+1;
SET_ARRAY(weight,0,n,0.);
weight[0]=2.;
for (int k=1; k<=(n/2-1); ++k)
weight[2*k-1]=2./(1.-4.*k*k);
weight[2*(n/2)-1]=(n-3.)/(2*(n/2)-1) -1.;
real_plan plan = make_real_plan(n);
real_plan_backward_fftpack(plan,weight);
kill_real_plan(plan);
for (int m=0; m<nrings; ++m)
weight[m]=weight[m+1];
for (int m=0; m<(nrings+1)/2; ++m)
{
theta[m]=pi*(m+1)/(nrings+1.);
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;
ofs[nrings-1-m]=(ptrdiff_t)((nrings-1-m)*stride_lat);
stride_[m]=stride_[nrings-1-m]=stride_lon;
weight[m]=weight[nrings-1-m]=weight[m]*2*pi/(n*nph[m]);
}
sharp_make_geom_info (nrings, nph, ofs, stride_, phi0_, theta, NULL, weight,
geom_info);
DEALLOC(theta);
DEALLOC(weight);
DEALLOC(nph);
DEALLOC(phi0_);
DEALLOC(ofs);
DEALLOC(stride_);
}
void sharp_make_mw_geom_info (int nrings, int ppring, double phi0,
int stride_lon, int stride_lat, sharp_geom_info **geom_info)
{