eikonal Traveltime computation by solving the eikonal equation
  
  tmap=eikonal(x,y,z,V,Sources,type);
 
   x,y,z : arrays defining the x, y, and z axis
   V: velocity field, with size (length(y),length(x),length(z));
   Sources [ndata,ndim] : Source positions
   type (optional): type of eikonal solver: [1]:Fast Marching(default), [2]:FD
 
   tmap [size(V)]: travel times computed everywhere in the velocity grid
 
 %Example (2D):
    x=[1:1:100];
    y=1:1:100;
    z=1;
    V=ones(100,100);V(:,1:50)=2;
    Sources = [10 50;75 50];
    t=eikonal(x,y,z,V,Sources);
    subplot(1,2,1);imagesc(x,y,t(:,:,1,1));axis image;colorbar
    subplot(1,2,2);imagesc(x,y,t(:,:,1,2));axis image;colorbar
 
  See also eikonal_traveltime