Several modifications and fixes.

- Add readGFC function to be able to read gfc files with headers.
- Change link to the example dataset and add a description.
- Brush up README.md
- Update ignore list.

.gitignore

@@ -49,3 +49,4 @@ octave-workspace
 
 # End of https://www.gitignore.io/api/matlab,linux
 results/
+input_data/

README.md

 # GRACETOOLS
 
-
 ## Overview
 
 GRACETOOLS is an archive of MATLAB software that can be used for gravity field recovery using GRACE type satellite observations.
 
+**Features**
+
+- The code is written using a batch least squares algorithm.
+- Three different fixed step numerical integration schemes are provided.
+- MATLAB parallel for-Loops (parfor) is used for calculation over arcs (days
+  here).
+- This code can be easily modified to run on the user's local parallel
+  computations clusters.
+
 ## Content
 
-* [Usage](#usage)
-* [Features](#features)
-* [Content](#content)
-* [Acknowledgments](#acknowledgments)
-* [Contributors](#contributors)
+- [Usage](#usage)
+- [Features](#features)
+- [Files](#files)
+- [Acknowledgments](#acknowledgments)
+- [Contributors](#contributors)
 
 ## Usage
 
+To be able to run the program download the following dataset:
 
-To be able to run the program download the following dataset and extract it into the `input_data` directory:
-- [Download dataset](https://wolke7.aei.mpg.de/index.php/s/DSoNjiclxl0S1UW)
+- [Download dataset](https://seafile.projekt.uni-hannover.de/f/3ee8fef6c6cb485489b4/?dl=1)
+
+Move the dataset into the `input_data` directory and extract it. Then delete
+the `input_data.zip` file. In a terminal the commands look like this from the
+GRACETOOLS main directory:
+
+```
+$ mv ~/Downloads/input_data.zip input_data/
+$ cd input_data/
+$ unzip input_data.zip
+$ rm -f input_data.zip
+```
 
-The directory structure of `input_data` should look lie this:
+Again from the GRACETOOLS main directory you can check the directory structure
+of the input_data/ directory with the following command:
+
+```
+$ tree input_data/
+```
+
+The output should look like this:
 
 ```
 input_data
@@ -43,16 +69,10 @@ input_data
 ├── EGM96.gfc
 └── GGM05S.gfc
 ```
-The main mfiles to run are: `gfr_parallel.m` and `continue_gfr_par_from_iteration.m`.
 
-## Features
+The main m-files to run are: `gfr_parallel.m` and `continue_gfr_par_from_iteration.m`.
 
-- The code is written using a batch least squares algorithm.
-- Three different fixed step numerical integration schemes are provided.
-- MATLAB parallel for-Loops (parfor) is used for calculation over arcs (days here).
-- This code can be easily modified to run on the user's local parallel computations clusters.
-
-## Content
+## Files
 
 | m-file                          | Description                                                                                                           |
 | :------------------------------ | :-------------------------------------------------------------------------------------------------------------------- |
@@ -94,7 +114,7 @@ The main mfiles to run are: `gfr_parallel.m` and `continue_gfr_par_from_iteratio
 
 ## Contributors
 
-- Neda Darbeheshti, neda.darbeheshti@aei.mpg.de
-- Florian Wöske, florian.woeske@zarm.uni-bremen.de
-- Axel Schnitger, axel.schnitger@aei.mpg.de
+- [Neda Darbeheshti](mailto:neda.darbeheshti@aei.mpg.de)
+- [Florian Wöske](mailto:florian.woeske@zarm.uni-bremen.de)
+- [Axel Schnitger](mailto:axel.schnitger@aei.mpg.de)
 

function_gfr/readGFC.m

+function gfc = readGFC(filename, verbosity)
+
+%------------------------------------------------------------------------------
+%
+% READGFC(FILENAME, VERBOSITY) loads a global gravity field model in form of a
+% spherical harmonic expansion (gcf-file).
+%
+% Input:
+%
+%   filename:  path to a .gfc file
+%   verbosity: if set to true additional output to command window. Default is
+%              false.
+%
+% Output:
+%
+%   gfc:        matrix containing l,m,C,S
+%
+% Usage:
+%
+%               readGFC('filename')
+%               readGFC('filename', true)
+%
+%------------------------------------------------------------------------------
+% Authors:
+% Axel Schnitger, AEI, Leibniz University Hannover  
+%------------------------------------------------------------------------------
+% Revision History
+% 2018-08-20: AS, intitial version    
+%------------------------------------------------------------------------------
+
+% Input arguments
+if nargin < 2 || verbosity == false
+    verbosity = false;
+elseif verbosity
+    tic
+    fprintf('\nStart reading:\t%s\n', filename)
+end
+
+fileID = fopen(filename);
+line = fgetl(fileID);
+if contains(line, 'gfc')
+    hasHeader = false;
+else
+    hasHeader = true;
+end
+
+formatSpec = '%s %f %f %f %f %f %f';
+
+if hasHeader
+    headerLines = 1;
+    while ~contains(line, 'end_of_head')
+        line = fgetl(fileID);
+        if isempty(line)
+            headerLines = headerLines + 1;
+            continue
+        end
+
+        keyword = textscan(line,'%s',1);
+        if(strcmp(keyword{1}, 'max_degree'))
+            tmp = textscan(line,'%s%d',1);
+            maxDegree = tmp{2};
+        end
+        if(strcmp(keyword{1}, 'radius'))
+            tmp = textscan(line,'%s%f',1);
+            radius = tmp{2};
+        end
+        if(strcmp(keyword{1}, 'earth_gravity_constant'))
+            tmp = textscan(line,'%s%f',1);
+            GM = tmp{2};
+        end
+        headerLines = headerLines + 1;
+    end
+    fclose(fileID);
+
+    fileID = fopen(filename);
+    gfcData = textscan(fileID, formatSpec, 'HeaderLines', headerLines);
+    fclose(fileID);
+
+elseif ~hasHeader
+    headerLines = 0;
+    fileID = fopen(filename);
+    gfcData = textscan(fileID, formatSpec);
+    fclose(fileID);
+    maxDegree=max(gfcData{2});
+end
+
+if verbosity
+    if hasHeader
+        fprintf('Headerlines:\t%u\n', headerLines)
+        fprintf('Size data:\t%u\n', length(gfcData{3}))
+        fprintf('max. Degree:\t%u\n', maxDegree)
+        fprintf('Radius:\t\t%f\n', radius)
+        fprintf('GM:\t\t%f\n', GM)
+    elseif ~hasHeader
+        fprintf('No header found.\n');
+        fprintf('Size data:\t%u\n', length(gfcData{3}))
+        fprintf('max. Degree:\t%u\n', maxDegree)
+    end
+    toc
+end
+
+gfc = [gfcData{2}, gfcData{3}, gfcData{4}, gfcData{5}];
+
+end
+

gfr_parallel.m

 %% GRACE gravity field recovery (GFR)
 %
-% GFR_PARALLEL is the main m-file preforming the gravity field estimation. It is
-% optimised for parallel computing using local and global parameters for
+% GFR_PARALLEL is the main m-file preforming the gravity field estimation. It
+% is optimised for parallel computing using local and global parameters for
 % different arcs. All necessary parameters and data are specified in the
 % following. You have to set a number of iterations you want to perform. With
 % the m-file continue_gfr_par_from_iteration.m you can continue a GFR from an
@@ -13,9 +13,6 @@
 % Neda Darbeheshti, AEI Hannover, 2018-07.
 
 %%
-clear all
-% close all;
-% clc;
 format longg;
 
 %% variable inputs
@@ -58,14 +55,14 @@ GM = 0.3986004415E+15;
 ae = 0.6378136300E+07;
 
 % reference for comparison
-ggm05s = importGravityField('GGM05S.gfc');
+ggm05s = readGFC('GGM05S.gfc');
 ggm05s = ggm05s(1:n_back,:); % cut to desired length
 ggm05s_cs = vec2cs([ggm05s(:,1) ggm05s(:,2)]',ggm05s(:,3),ggm05s(:,4));
 % d_vec_i = ggm05s(:,3:4)-gravityf(:,3:4);
 % d_vec_i = [ggm05s(:,1:2) d_vec_i];
 
 %Load a-priori/ reference gravity field
-egm96 = importGravityField('EGM96.gfc');
+egm96 = readGFC('EGM96.gfc');
 egm96 = egm96(1:n_back,:); % cut to desired length
 egm96_cs = vec2cs([egm96(:,1) egm96(:,2)]',egm96(:,3),egm96(:,4));
 
@@ -305,7 +302,3 @@ for i = 1:ItrNo_max+1
     semilogy(2:lmaxcs,dv_save(i,:),'.-','LineWidth',2,'MarkerSize',16,'DisplayName', str);
 end
 
-
-
-
-