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inlib
1.2.0
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inlib
1.2.0
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Functions | |
| int | fmodi (int a_x, int a_y) |
| void | mk_xy2pix (int *x2pix, int *y2pix) |
| bool | ang2pix_nest (std::ostream &a_out, long a_nside, double a_theta, double a_phi, long &a_ipix) |
| bool | ang2pix_ring (std::ostream &a_out, long a_nside, double a_theta, double a_phi, long &a_ipix) |
| bool inlib::healpix::ang2pix_nest | ( | std::ostream & | a_out, |
| long | a_nside, | ||
| double | a_theta, | ||
| double | a_phi, | ||
| long & | a_ipix | ||
| ) | [inline] |
Definition at line 57 of file healpix.
{
// gives the pixel number ipix (NESTED) corresponding to angles theta and phi
//
// the computation is made to the highest resolution available (nside=8192)
// and then degraded to that required (by integer division)
// this doesn't cost more, and it makes sure that the treatement of
// round-off will be consistent for every resolution
int ns_max = 8192;
if( a_nside<1 || a_nside>long(ns_max) ) {
a_out << "inlib::healpix::ang2pix_nest :"
<< " nside out of range " << (int)a_nside
<< std::endl;
return false;
}
if( a_theta<0. || a_theta>pi() ) {
a_out << "inlib::healpix::ang2pix_nest :"
<< " theta out of range " << a_theta
<< std::endl;
return false;
}
static int x2pix[128], y2pix[128];
static bool setup_done = false;
if(!setup_done ) {
mk_xy2pix(x2pix,y2pix);
setup_done = true;
}
if( a_phi>=two_pi() ) a_phi = a_phi - two_pi();
else if( a_phi<0. ) a_phi = a_phi + two_pi();
double tt = a_phi / half_pi(); // in [0,4[
double z = ::cos(a_theta);
double za = ::fabs(z);
double z0 = 2./3.;
int face_num,jp,jm;
long ifp, ifm;
int ix, iy, ipf, ntt;
if( za<=z0 ) { // equatorial region
// (the index of edge lines increase when the longitude=phi goes up)
jp = (int)::floor(ns_max*(0.5 + tt - z*0.75));// ascending edge line index
jm = (int)::floor(ns_max*(0.5 + tt + z*0.75));// descending edge line index
// finds the face
ifp = jp / ns_max; // in {0,4}
ifm = jm / ns_max;
if( ifp==ifm ) face_num = fmodi(ifp,4) + 4; // faces 4 to 7
else if( ifp<ifm ) face_num = fmodi(ifp,4); // (half-)faces 0 to 3
else face_num = fmodi(ifm,4) + 8; // (half-)faces 8 to 11
ix = fmodi(jm, ns_max);
iy = ns_max - fmodi(jp, ns_max) - 1;
} else { // polar region, za > 2/3
ntt = (int)::floor(tt);
if( ntt>=4 ) ntt = 3;
double tp = tt - ntt;
double tmp = ::sqrt( 3.*(1. - za) ); // in ]0,1]
// (the index of edge lines increase when distance from the closest pole
// goes up)
// line going toward the pole as phi increases
jp = (int)::floor( ns_max * tp * tmp );
// that one goes away of the closest pole
jm = (int)::floor( ns_max * (1. - tp) * tmp );
jp = (int)(jp < ns_max-1 ? jp : ns_max-1);
jm = (int)(jm < ns_max-1 ? jm : ns_max-1);
// finds the face and pixel's (x,y)
if( z>=0 ) {
face_num = ntt; // in {0,3}
ix = ns_max - jm - 1;
iy = ns_max - jp - 1;
}
else {
face_num = ntt + 8; // in {8,11}
ix = jp;
iy = jm;
}
}
int ix_low = fmodi(ix,128);
int ix_hi = ix/128;
int iy_low = fmodi(iy,128);
int iy_hi = iy/128;
ipf = (x2pix[ix_hi]+y2pix[iy_hi]) * (128 * 128)+
(x2pix[ix_low]+y2pix[iy_low]);
ipf = (long)(ipf / ::pow(ns_max/a_nside,2)); // in {0, a_nside**2 - 1}
a_ipix =(long)( ipf + face_num*::pow(a_nside,2)); // in {0, 12*a_nside**2-1}
return true;
}
| bool inlib::healpix::ang2pix_ring | ( | std::ostream & | a_out, |
| long | a_nside, | ||
| double | a_theta, | ||
| double | a_phi, | ||
| long & | a_ipix | ||
| ) | [inline] |
MOD(tt,1.d0)
Definition at line 164 of file healpix.
{
// gives the pixel number ipix (RING)
// corresponding to angles theta and phi
long ns_max=8192;
if( a_nside<1 || a_nside>ns_max ) {
a_out << "inlib::healpix::ang2pix_ring :"
<< " nside out of range " << (int)a_nside
<< std::endl;
return false;
}
if( a_theta<0. || a_theta>pi() ) {
a_out << "inlib::healpix::ang2pix_ring :"
<< " theta out of range " << a_theta
<< std::endl;
return false;
}
if( a_phi>=two_pi() ) a_phi = a_phi - two_pi();
else if( a_phi<0. ) a_phi = a_phi + two_pi();
double z = ::cos(a_theta);
double za = ::fabs(z);
double tt = a_phi / half_pi();// ! in [0,4)
double z0=2.0/3.0;
int nl2 = 2*a_nside;
int nl4 = 4*a_nside;
int ncap = nl2*(a_nside-1);// ! number of pixels in the north polar cap
int npix = 12*a_nside*a_nside;
int jp, jm, ipix1;
int ir, ip, kshift;
if( za <= z0 ) {
jp = (int)::floor(a_nside*(0.5+tt-z*0.75)); //index of ascending edge line
jm = (int)::floor(a_nside*(0.5+tt+z*0.75)); //index of descending edge line
ir = a_nside + 1 + jp - jm; //in {1,2n+1} (ring number counted from z=2/3)
kshift = 0;
if (fmodi(ir,2)==0) kshift = 1;// ! kshift=1 if ir even, 0 otherwise
ip = (int)::floor( double(jp+jm-a_nside+kshift+1)/2) + 1; //in {1,4n}
if( ip>nl4 ) ip = ip - nl4;
ipix1 = ncap + nl4*(ir-1) + ip ;
} else {
double tp = tt - ::floor(tt);
double tmp = ::sqrt( 3.*(1. - za) );
jp = (int)::floor( a_nside * tp * tmp ); //increasing edge line index
jm = (int)::floor( a_nside * (1. - tp) * tmp );//decreasing edge line index
ir = jp + jm + 1; //ring number counted from the closest pole
ip = (int)::floor( tt * ir ) + 1;// ! in {1,4*ir}
if( ip>4*ir ) ip = ip - 4*ir;
ipix1 = 2*ir*(ir-1) + ip;
if( z<=0. ) {
ipix1 = npix - 2*ir*(ir+1) + ip;
}
}
a_ipix = ipix1 - 1;// ! in {0, npix-1}
return true;
}
| int inlib::healpix::fmodi | ( | int | a_x, |
| int | a_y | ||
| ) | [inline] |
| void inlib::healpix::mk_xy2pix | ( | int * | x2pix, |
| int * | y2pix | ||
| ) | [inline] |
Definition at line 25 of file healpix.
{
// sets the array giving the number of the pixel lying in (x,y)
// x and y are in {1,128}
// the pixel number is in {0,128**2-1}
//
// if i-1 = sum_p=0 b_p * 2^p
// then ix = sum_p=0 b_p * 4^p
// iy = 2*ix
// ix + iy in {0, 128**2 -1}
int i, K,IP,I,J,ID;
for(i = 0; i < 127; i++) x2pix[i] = 0;
for( I=1;I<=128;I++ ) {
J = I-1;// !pixel numbers
K = 0;//
IP = 1;//
truc : if( J==0 ) {
x2pix[I-1] = K;
y2pix[I-1] = 2*K;
}
else {
ID = fmodi(J,2);
J = J/2;
K = IP*ID+K;
IP = IP*4;
goto truc;
}
}
}
1.7.5.1