Title= "simulation data"
VARIABLES= "X","Y","Z","U","V","W","RHO"
ZONE T= "BOX",I= 100,J=321,K=100,F= POINT
0 0 0 0.000252868 0.00386761 -0.00194455 1000.01
1 0 0 -0.000252631 -0.00258331 0.00188909 1000.01
2 0 0 0.000252594 0.00441002 -0.00183506 1000.01
3 0 0 -0.000252256 -0.0019755 0.00178188 1000
4 0 0 0.000252931 0.00492305 -0.00173004 1000
...

% read data from tecplot file, and save the variables to mat
% filename: the name of the tecplot file including the extensions
% var: the data of variables, is a four dimensions array, the last dimension is the the number of variable
% var_name: the name of the variables, is a cell
% var_num: the number of the variables
function [var,var_name,var_num] = tecplot2mat_3D(filename)
%% tecplot data file read
% open the file
fid = fopen(filename);% read the second line of data file
[~] = fgetl(fid);
str = fgetl(fid);% get the number of the variables
o1 = regexpi(str,'"','start');
var_num = length(o1)/2;% get the name of the variables
var_name = cell(1,var_num);
for i = 1:var_numvar_name{1,i} = str(o1(2*i-1)+1:o1(2*i)-1);
end% read the data
strformat = repmat('%f',1,var_num);
data = textscan(fid,strformat,'headerlines',1);
data = cell2mat(data);% close the file
fclose(fid);%% reshape data
% get discrete points
xi = sort(unique(data(:,1)));
yi = sort(unique(data(:,2)));
zi = sort(unique(data(:,3)));% number of the discrete points
num_x = length(xi);
num_y = length(yi);
num_z = length(zi);% initialize the three demonsions array
var = zeros(num_x,num_y,num_z,var_num);% assignment the array according to the data
for n = 1:size(data,1)% method 1: we don't know the relationship between the number and the index, we must find the index according to the value    %     index_x = find( data(n,1) == xi );%     index_y = find( data(n,2) == yi );%     index_z = find( data(n,3) == zi );% method 2: we know the relationship between the value and the index, we can directly access the index index_x = data(n,1) + 1;index_y = data(n,2) + 1;index_z = data(n,3) + 1;% access the datafor i = 1:var_numvar(index_x,index_y,index_z,i) = data(n,i);end
endfprintf('reshape the data\n');%% data save to mat
index_str = find( '.' == filename );
if isempty(index_str)
elsefilename = filename( 1:index_str-1 );
end
eval(['save ',filename,'.mat var var_name var_num;']);fprintf('save the data\n');
end

% read data from tecplot file, and save the variables to mat
% filename: the name of the tecplot file including the extensions
% var: the data of variables, is a three dimensions array, the last dimension is the the number of variable
% var_name: the name of the variables, is a cell
% var_num: the number of the variables, is a number
function [var,var_name,var_num] = tecplot2mat_2D(filename)
%% tecplot data file read
% open the file
fid = fopen(filename);% read the second line of data file
[~] = fgetl(fid);
str = fgetl(fid);% get the number of the variables
o1 = regexpi(str,'"','start');
var_num = length(o1)/2;% get the name of the variables
var_name = cell(1,var_num);
for i = 1:var_numvar_name{1,i} = str(o1(2*i-1)+1:o1(2*i)-1);
end% read the data
strformat = repmat('%f',1,var_num);
data = textscan(fid,strformat,'headerlines',1);
data = cell2mat(data);% close the file
fclose(fid);%% reshape data
% get discrete points
xi = sort(unique(data(:,1)));
yi = sort(unique(data(:,2)));% number of the discrete points
num_x = length(xi);
num_y = length(yi);% initialize the three demonsions array
var = zeros(num_x,num_y,var_num);% assignment the array according to the data
for n = 1:size(data,1)% method 1: we don't know the relationship between the number and the index, we must find the index according to the value%     index_x = find(data(n,1) == xi);%     index_y = find(data(n,2) == yi);% method 2: we know the relationship between the value and the index, we can directly access the index index_x = data(n,1) + 1;index_y = data(n,2) + 1;% access the datafor i = 1:var_numvar(index_x,index_y,i) = data(n,i);end
endfprintf('reshape the data\n');%% data save to mat
index_str = find( '.' == filename );
if isempty(index_str)
elsefilename = filename( 1:index_str-1 );
end
eval(['save ',filename,'.mat var var_name var_num;']);fprintf('save the data\n');
end

clc;clear;
close all;filename = 'U3D.dat';
[var,var_name,var_num] = tecplot2mat_3D(filename);for i = 1:var_numeval([var_name{1,i},'=var(:,:,:,i);']);
end