function s = RandStream(type, varargin) 

%RANDSTREAM Create a random number stream.

%   S = RandStream('GENTYPE') creates a random number stream that uses the

%   uniform pseudorandom number generator algorithm specified by GENTYPE.

%   Type "RandStream.list" for a list of possible values for GENTYPE, or

%   see <a href="matlab:helpview([docroot '\techdoc\math\math.map'],'choose_random_number_generator')">Choosing a Random Number Generator</a> for details on these generator

%   algorithms.

%

%   One you have created a random stream, you can use RANDSTREAM.setGlobalStream

%   to make it the global stream, so that RAND, RANDI, and RANDN draw values

%   from it.

%

%   [ ... ] = RandStream('GENTYPE', 'PARAM1',val1, 'PARAM2',val2, ...) allows

%   you to specify optional parameter name/value pairs to control creation of

%   the stream.  Parameters are:

%

%      Seed            - a non-negative scalar integer seed with which to

%                        initialize the stream, or 'shuffle' to create a seed

%                        based on the current time.  Default is 0.

%      NormalTransform - the transformation algorithm that RANDN(S, ...) uses

%                        to generate normal pseudorandom values from uniform

%                        pseudorandom values.  The property value is one of

%                        'Ziggurat' (the default), 'Polar', or 'Inversion'.

%

%   Streams created using RandStream may not be independent from each other.

%   Use RandStream.CREATE to create multiple streams that are independent.

%

%   Examples:

%

%      Create a random number stream, make it the global stream, and save and

%      restore its state to reproduce the output of RANDN:

%         s = RandStream('mrg32k3a');

%         RandStream.setGlobalStream(s);

%         savedState = s.State;

%         z1 = randn(1,5)

%         s.State = savedState;

%         z2 = randn(1,5) % z2 contains exactly the same values as z1

%

%      Return RAND, RANDI, and RANDN to their default startup settings:

%         s = RandStream('mt19937ar','Seed',0)

%         RandStream.setGlobalStream(s);

%

%      Replace the current global random number stream with a stream whose

%      seed is based on the current time, so RAND, RANDI, and RANDN will

%      return different values in different MATLAB sessions.  NOTE: It is

%      usually not desirable to do this more than once per MATLAB session.

%         s = RandStream('mt19937ar','Seed','shuffle');

%         RandStream.setGlobalStream(s);

%

%   See also RANDSTREAM, RANDSTREAM.CREATE, RANDSTREAM.LIST, RNG,

%            RANDSTREAM.GETGLOBALSTREAM, RANDSTREAM.SETGLOBALSTREAM,

%            RANDSTREAM/RAND, RANDSTREAM/RANDI, RANDSTREAM/RANDN.

            if nargin < 1 

                error(message('MATLAB:RandStream:TooFewInputs'));

            end

            type = convertStringsToChars(type); 

            pnames = {'seed' 'normaltransform' 'parameters'}; 

            dflts =  {    0                []           [] }; 

            [seed,randnalg,params] = getargs(pnames, dflts, varargin{:}); 

            if ~ischar(type) 

                error(message('MATLAB:RandStream:InvalidRNGType'));

            end

            if ischar(seed) && isequal(lower(seed),'shuffle') 

                seed = RandStream.shuffleSeed;

            elseif ~isnumeric(seed) || ~isreal(seed) ||~isscalar(seed) || ~(0<=seed && seed<2^32) 

                % Allow non-integer seed so that sum(100*clock) works.  Will truncate below.

                error(message('MATLAB:RandStream:BadSeed'));

            end

            if isempty(params) 

                % none given, it will be defaulted to zero below

            elseif ~isnumeric(params) || ~isreal(params) || ~isvector(params) ...

                                      || ~all(params == round(params)) || ~all(params >= 0)

                error(message('MATLAB:RandStream:BadParams'));

            elseif any(strcmpi(type,RandStream.BuiltinTypes))

                error(message('MATLAB:RandStream:ParamNotValid', type));

            end    

            s.Type = RandStream.algName(type(:)'); 

            s.Seed = uint32(floor(seed)); % truncate if not integer 

            s.Params = uint64(params); % possibly empty 

            s.NumStreams = uint64(1); 

            s.StreamIndex = uint64(1); % stored one-based 

            s.SpawnIncr = uint64(1); 

            s.StreamID = builtin('_RandStream_create_mex',s.Type,s.NumStreams,s.StreamIndex,s.Seed,s.Params); 

            if ~isempty(randnalg), set(s,'NormalTransform',randnalg); end 

        end