Connect to Quandl
Load credential and connect to Quandl

c = Quandl.api_key('xxxxxxxxxxxxxxx'); % You need to enter your Quandl key here
%c = quandl(quandlKey);
clearvars quandlKey

Set symbols for retrieving data
symbol1 = {'BCHAIN/MKPRU', ...% Bitcoin Market Price USD
'BCHAIN/MWNUS', ...% Bitcoin My Wallet Number of Users
'BCHAIN/DIFF',  ...% Bitcoin Difficulty};   % Total Bitcoins

 Retrieve data from Quandl in the past 2,000 days
 nDays = 2000;
 d = cell(1,numel(symbol1));
 d{1} = Quandl.get(symbol1{1}, today - nDays,today - 1);
 T = d{1};
 for i = 2:numel(symbol1)
      d{i} = Quandl.get(symbol1{i}, today - nDays,today - 1);
      T = synchronize(T,d{i});
 end

Create new variable names
symbol2 = regexprep(symbol1,'BCHAIN/',''); % Tighten symbols' name
T.Properties.VariableNames = symbol2;