Local maps

A local map is a 2 dimensional array, with i as column index and j as row index. The map is supposed to lie on a plan tangent to the celestial sphere in a point whose coordinates are (x0,y0) on the local map and (theta0, phi0) on the sphere. The range of the map is defined by two values of angles covered respectively by all the pixels in x direction and all the pixels in y direction (SetSize()). Default value of (x0, y0) is middle of the map, center of pixel(nx/2, ny/2).

Internally, a map is first defined within this reference plane and tranported until the point (theta0, phi0) in such a way that both axes are kept parallel to meridian and parallel lines of the sphere. The user can define its own map with axes rotated with respect to reference axes (this rotation is characterized by angle between the local parallel line and the wanted x-axis- method SetOrigin(...))

The example below shows creating and filling of a LocalMap with 4 columns and 5 rows. The origin is set to default. The map covers a sphere portion defined by two angles of 30. degrees (methods SetOrigin() and SetSize() must be called in order to completely define the map).

#include "localmap.h"  
//..............       
  LocalMap<r_4> locmap(4,5);
  for (int k=0; k<locmap.NbPixels();k++) locmap(k)=10.*k;
  locmap.SetOrigin();
  locmap.SetSize(30.,30.);