Add support for Model repo

User supplied models can now be obtained through the new repo:
https://www.github.com/spinw/Models
Or on the MATLAB search path with files starting in 'swm_*'.
Former-commit-id: 39f2331

Author: wardsimon

swfiles/sw_model.m

@@ -21,7 +21,10 @@
 %                   120\\deg angle and optimised magnetic structure.
 %   * `'squareAF'`  Square lattice antiferromagnet.
 %   * `'chain'`     Chain with further neighbor interactions.
-% 
+%   * `swm_*`       Custom models which are in the matlab path can be 
+%                 evaluated. Checkout: 
+%                 https://www.github.com/spinw/Models for pre-made models.
+%
 % `param`
 % : Input parameters of the model, row vector which gives the values of the
 %   Heisenberg exchange for first, second, thirs etc. neighbor bonds stored
@@ -49,6 +52,7 @@
 end
 
 fprintf0(fid,'Preparing ''%s'' model ...\n',model);
+modelSearch = 'swm_';
 
 obj = spinw;
 
@@ -108,7 +112,26 @@
             end
         end
     otherwise
-        error('sw_model:WrongINput','Model does not exists!')
+        % All paths
+        allPaths =  strsplit(path,':');
+        % Remove the builtin functions
+        allPaths =  allPaths(~strncmp(allPaths,fullfile(matlabroot, 'toolbox'), length(fullfile(matlabroot, 'toolbox'))));
+        relPaths = allPaths(~strncmp(allPaths,fullfile(matlabroot, 'example'), length(fullfile(matlabroot, 'example'))));
+        % Get all files
+        allFiles = cellfun(@(x) dir(x), relPaths, 'UniformOutput', false);
+        allFiles = cellfun(@(x) {x.name}, allFiles, 'UniformOutput', false);
+        allFiles = [allFiles{:}];
+        % Search for files which are models
+        relFiles = cellfun(@(x) x(1:end-2) ,allFiles(strncmp(allFiles, modelSearch, 3)),'UniformOutput',false);
+        if ~any(strcmp(model, relFiles))
+            error('sw_model:WrongINput','Model does not exists!')
+        end
+        % Evaluate the model
+        try
+            obj = feval(model, param);        
+        catch ME
+            error('sw_model:WrongINput','This model has an error!')
+        end
 end
 
 fprintf0(fid,'... ready!\n');