function M = viewfrom(azimuth,elevation)
%
% Transformation to right-up-towardme coordinates
% from East-North-Up coordinates, as viewed from
% given azimuth (measured CCW from East)
% and elevation angle (measured up from E-N plane.
% All angles in radians.
%
sa = sin(azimuth);
ca = cos(azimuth);
se = sin(elevation);
ce = cos(elevation);
M = [-sa,ca,0;-ca*se,-sa*se,ce;ca*ce,sa*ce,se];