init2dsnapshot.m

Spectral Element Method for wave propagation and rupture dynamics.

% indx = Init2dSnapshot(iglob)
% [indx,coord_new] = Init2dSnapshot(iglob,coord)
%
% PURPOSE	Initializes grid data for Plot2dSnapshot
%
% INPUT		iglob(ngll,ngll,nel) local to global numbering map
%		coord(npoin,2) 	coordinates of the nodes
%
% OUTPUT	indx(:,4) 	vertices of each GLL cell
%		coord_new(:,2) 	reshaped coord 
%
% NOTE		coord and coord_new are required only to plot element-wise fields
%		(stress, strain, material properties)
%
function [indx,coord_new] = Init2dSnapshot(iglob,coord)

[NGLL,NGLL,NEL] = size(iglob);
indx = zeros(NEL*(NGLL-1)^2, 4);

% node-wise storage
if nargin<2

  ip=0;
  for e=1:NEL,
    for i=1:NGLL-1,
    for j=1:NGLL-1,
      ip = ip+1;
      indx(ip,:) = [iglob(i,j,e) iglob(i+1,j,e) iglob(i+1,j+1,e) iglob(i,j+1,e)];
    end
    end
  end

% element-wise storage
else
 
  if nargout<2, error('Too few outputs'), end

  coord_new = coord(iglob(:),1:2);

  iglob0 = reshape( (1:NGLL*NGLL)', NGLL,NGLL);
  indx0 = zeros((NGLL-1)^2, 4);
  ip=0;
  for i=1:NGLL-1,
  for j=1:NGLL-1,
    ip = ip+1;
    indx0(ip,:) = [iglob0(i,j) iglob0(i+1,j) iglob0(i+1,j+1) iglob0(i,j+1)];
  end
  end

  blocksize = (NGLL-1)^2;
  for e=1:NEL,
    ip = (e-1)*blocksize;
    indx(ip+1:ip+blocksize,:) = indx0 + (e-1)*NGLL^2;
  end

end