function settings = rng(arg1,arg2)

%RNG Control the random number generator used by RAND, RANDI, and RANDN.

%   RNG(SD) seeds the random number generator using the non-negative

%   integer SD so that RAND, RANDI, and RANDN produce a predictable

%   sequence of numbers.

%

%   RNG('shuffle') seeds the random number generator based on the current

%   time so that RAND, RANDI, and RANDN produce a different sequence of

%   numbers after each time you call RNG.

%

%   RNG(SD,GENERATOR) and RNG('shuffle',GENERATOR) additionally specify the

%   type of the random number generator used by RAND, RANDI, and RANDN.

%   GENERATOR is one of:

%

%       Generator              Description

%      ------------------------------------------------------------------ 

%      'twister'               Mersenne Twister

%      'simdTwister'           SIMD-oriented Fast Mersenne Twister

%      'combRecursive'         Combined Multiple Recursive

%      'multFibonacci'         Multiplicative Lagged Fibonacci

%      'philox'                Philox generator with 10 rounds

%      'threefry'              Threefry generator with 20 rounds

%      'v5uniform'             Legacy MATLAB 5.0 uniform generator

%      'v5normal'              Legacy MATLAB 5.0 normal generator

%      'v4'                    Legacy MATLAB 4.0 generator

%

%   RNG('default') puts the settings of the random number generator used by

%   RAND, RANDI, and RANDN to their default values so that they produce the

%   same random numbers as if you restarted MATLAB. In this release, the

%   default settings are the Mersenne Twister with seed 0.

%

%   SCURR = RNG returns the current settings of the random number generator

%   used by RAND, RANDI, and RANDN. The settings are returned in a

%   structure SCURR with fields 'Type', 'Seed', and 'State'.

%    

%   RNG(S) restores the settings of the random number generator used by

%   RAND, RANDI, and RANDN back to the values captured previously by

%   S = RNG.

%

%   SPREV = RNG(...) returns the previous settings of the random number

%   generator used by RAND, RANDI, and RANDN before changing the settings.

%

%      Example 1: Retrieve and Restore Generator Settings

%         s = rng           % get the current generator settings

%         x = rand(1,5)     % RAND generates some values

%         rng(s)            % restore the generator settings

%         y = rand(1,5)     % generate the same values so x and y are equal

% 

%      Example 2: Restore Settings for Legacy Generator

%         prevS = rng(0,'v5uniform') % use legacy generator, save previous settings

%         x = rand                   % legacy startup value .9501

%         rng(prevS)                 % restore the previous settings

%

%   See <a href="matlab:helpview([docroot '\techdoc\math\math.map'],'update_random_number_generator')">Replace Discouraged Syntaxes of rand and randn</a> to use RNG to replace

%   RAND or RANDN with the 'seed', 'state', or 'twister' inputs.

%

%   See also RAND, RANDI, RANDN, RandStream, NOW.

%   See <a href="http://www.mathworks.com/access/helpdesk/help/techdoc/math/brn4ixh.html#brvku_2">Choosing a Random Number Generator</a> for details on these generators.

%   Copyright 2010-2018 The MathWorks, Inc. 

if nargin == 0 || nargout > 0 

    % With no inputs, settings will be returned even when there's no outputs

    s = RandStream.getGlobalStream();

    if strcmpi(s.Type,'legacy')

        settings = struct('Type','Legacy','Seed',legacySeedStr(),'State',{s.State});

    else

        settings = struct('Type',RandStream.compatName(s.Type),'Seed',s.Seed,'State',{s.State});

    end

end 

if nargin > 0 

    arg1 = convertStringsToChars(arg1); 

    if isstruct(arg1) && isscalar(arg1) 

        inSettings = arg1;

        if nargin > 1

            error(message('MATLAB:rng:maxrhs'));

        elseif ~isempty(setxor(fieldnames(inSettings),{'Type','Seed','State'}))

            throw(badSettingsException);

        end

        if strcmpi(inSettings.Type,'legacy')

            handleLegacyStruct(inSettings); % restores the legacy stream state

        else

            % Create a new stream as specified, then set its state

            try

                s = RandStream(inSettings.Type,'Seed',inSettings.Seed);

                s.State = inSettings.State;

            catch me

                throw(badSettingsException);

            end

            RandStream.setGlobalStream(s);

        end

    else 

        if isnumeric(arg1) && isscalar(arg1) % rng(seed) or rng(seed,gentype) 

            seed = arg1; 

            if nargin == 1 

                gentype = getCurrentType; 

            else

                arg2 = convertStringsToChars(arg2);

                gentype = arg2;

                if ~ischar(gentype)

                    error(message('MATLAB:rng:badSecondOpt'));

                elseif strcmpi(gentype,'legacy')

                    errorLegacyGenType;

                end

            end 

        elseif ischar(arg1)

            if strcmpi(arg1,'shuffle') % rng('shuffle') or rng('shuffle',gentype)

                seed = RandStream.shuffleSeed;

                if nargin == 1

                    gentype = getCurrentType;

                else

                    arg2 = convertStringsToChars(arg2);

                    gentype = arg2;

                    if ~ischar(gentype)

                        error(message('MATLAB:rng:badSecondOpt'));

                    elseif strcmpi(gentype,'legacy')

                        errorLegacyGenType;

                    end

                end

            elseif strcmpi(arg1,'default') % rng('default')

                if nargin > 1

                    error(message('MATLAB:rng:maxrhs'));

                end

                seed = 0;

                gentype = RandStream.DefaultStartupType;

            else % possibly rng(gentype) or rng(gentype,seed)

                error(message('MATLAB:rng:badFirstOpt'));

            end

        else

            error(message('MATLAB:rng:badFirstOpt'));

        end 

        % Create a new stream using the specified seed

        try 

            s = RandStream(gentype,'Seed',seed); % RandStream handles the compatibility names 

        catch me

            if strcmp(me.identifier,'MATLAB:RandStream:create:UnknownRNGType')

                error(message('MATLAB:rng:unknownRNGType',gentype));

            elseif strcmp(me.identifier,'MATLAB:RandStream:BadSeed')

                error(message('MATLAB:rng:badSeed'));

            else

                throw(me);

            end

        end 

        RandStream.setGlobalStream(s); 

    end 

end