sweepmatrix

 SWEEPMATRIX precalulates the x and y coordinates for the ray pixels used in CIRCSWEEP.
 
 SWEEPMATRIX sets up the matrices which when cropped properly can be
 directly used by CIRCSWEEP to find the ray sum results. The main use for
 this function is to improve computational efficiency.
 
 USAGE:
     [sweepmatx,sweepmaty]=sweepmatrix(img)
 
 INPUTS:
     img: image (the main concern is the size of the image
 
 OUTPUTS:
     sweepmatx: x coordinate sweep matrix, each column corresponds to the
     x coordinates of the pixels that lie under a ray of a certain angle.
     Angles increase progressively from 0 to 360 along dimension 2 of the
     array.
 
     sweepmaty: y coordinate sweep matrix, each column corresponds to the
     y coordinates of the pixels that lie under a ray of a certain angle.

0001 function [sweepmatx,sweepmaty]=sweepmatrix(img)
0002 % SWEEPMATRIX precalulates the x and y coordinates for the ray pixels used in CIRCSWEEP.
0003 %
0004 % SWEEPMATRIX sets up the matrices which when cropped properly can be
0005 % directly used by CIRCSWEEP to find the ray sum results. The main use for
0006 % this function is to improve computational efficiency.
0007 %
0008 % USAGE:
0009 %     [sweepmatx,sweepmaty]=sweepmatrix(img)
0010 %
0011 % INPUTS:
0012 %     img: image (the main concern is the size of the image
0013 %
0014 % OUTPUTS:
0015 %     sweepmatx: x coordinate sweep matrix, each column corresponds to the
0016 %     x coordinates of the pixels that lie under a ray of a certain angle.
0017 %     Angles increase progressively from 0 to 360 along dimension 2 of the
0018 %     array.
0019 %
0020 %     sweepmaty: y coordinate sweep matrix, each column corresponds to the
0021 %     y coordinates of the pixels that lie under a ray of a certain angle.
0022 
0023 theta=pi()/90:pi()/90:2*pi();
0024 win=min(size(img));
0025 r=1:win;
0026 % get grids
0027 [thetag,rg]=meshgrid(theta,r);
0028 sweepmatx=round(rg.*cos(thetag));
0029 sweepmaty=round(rg.*sin(thetag));