matlab_notes.txt

Matlab won't restart:
stop all java processes
If that doesn't work, open matlab on the command prompt with '-nojvm' and try this:
clear all;
rehash;
rehash toolboxreset;


Matlab won't release lock on mex file:
clear mex
Or try any of the following:
clear <mex_file_name>
MUNLOCK
mexUnlock


Comment block:
%{ ... %}


Switch to command window:
ctrl-0
Switch to editor:
ctrl-shift-0


Generally prefer numel() to length(). numel is number of elements, length is length of greatest dimension.
numel(A) == prod(size(A))
length(A) == max(size(A))


Preallocating with A(1000,1000) = 0 is generally faster than A = zeros(1000,1000). This is somewhat counterintuitive, but apparently the former is akin to calloc and the later to malloc + memset.
For cell arrays, initializing with the cell() function is preferred.
For non-double data, A = zeros(1000,1000,'int8') is faster than A = int8(zeros(1000,1000)), but A(1000,1000) = int8(0) is still even faster.
Note that this is true for Windows but might not be for Linux or Mac


Display last warning identifier:
w = warning('query','last')


List all environment variables in Matlab:
http://stackoverflow.com/questions/20004955/list-all-environment-variables-in-matlab

% returned as a Java map
map = java.lang.System.getenv();

% build MATLAB map
% (Windows env. vars. are case-insensitive)
m = containers.Map(...
    upper(cell(map.keySet.toArray)), ...   % keys
    cell(map.values.toArray));             % values

% access variables by name
disp(m('OS'))

% print all environment variables
keys = m.keys;
for i=1:numel(keys)
    fprintf('%s=%s\n', keys{i}, m(keys{i}));
end

% Get command history:
% http://www.mathworks.com/matlabcentral/answers/239151-any-way-to-get-2015a-working-with-two-environments
historypath = com.mathworks.mlservices.MLCommandHistoryServices.getSessionHistory;
% No known way to load or set the history, though.

% Get list of open files:
docArray = matlab.desktop.editor.getAll;
fNames = cell(1,length(docArray));
for fIdx = 1:length(docArray)
    fNames{fIdx} = docArray(fIdx).Filename;
end

% Open a list of files:
for fIdx = 1:length(fNames)
    matlab.desktop.editor.openDocument(fNames{fIdx});
end