% Save MATALB variables in VTK format
% x is a list of points
% y is a list of values in the x points
% VarName is the Variable Name
%
% Example:
%
% x=[0:0.1:2*pi];
% y=sin(x);
% plot(x,y);
% savevtk_xy(x,y,'sin(x)');
%
% Coded by Sebastian Jardi Estadella
% http://www.tinet.org/~sje/index_en.htm
%

function [fd,err]=savevtk_xy(x,y,VarName)

nx=length(x);
ny=length(y);
if nx~=ny 
  disp('X and Y have to be of the same length');
  break;
end

filename=sprintf('%s.vtk',VarName);

fd=fopen(filename,'w');		% Open for write and create file if required
										% and deletes previous contents.
fprintf(fd,'# vtk DataFile Version 2.0\n');   % Start to write.
err=fclose(fd);							% closes file.                              

fd=fopen(filename,'a');		% Open to append data

fprintf(fd,'Structured Grid\n');
fprintf(fd,'ASCII\n');
fprintf(fd,'\n');
fprintf(fd,'DATASET RECTILINEAR_GRID\n');
fprintf(fd,'DIMENSIONS %d %d %d\n',nx,1,1);

fprintf(fd,'X_COORDINATES %d double\n',nx);
for i=1:nx
  fprintf(fd,'%e\n',x(i));  
end
fprintf(fd,'\n');

fprintf(fd,'Y_COORDINATES 1 double\n');
fprintf(fd,'0 \n');

fprintf(fd,'Z_COORDINATES 1 double\n');
fprintf(fd,'0 \n');

fprintf(fd,'\n');
fprintf(fd,'POINT_DATA %d\n',nx);
fprintf(fd,'SCALARS ');
fprintf(fd,VarName);
fprintf(fd,' double 1\n');
fprintf(fd,'LOOKUP_TABLE TableName\n');
for i=1:length(y)
  fprintf(fd,'%e\n',y(i));  
end
fprintf(fd,'\n');

err=fclose(fd);