Thank you for the details. We are looking into the conversion code to make it faster. Will update you shortly..

Thank you for your question.

Frankly, we didn't expect that conversion to string would be an important part of numerical computations (e.g. running in O(n^2) loop or similar). That is why we didn't optimize it to the maximum extent. I guess your case is very special in this regard.

What do you with the number after conversion (e.g. numeric computations)? I am pretty sure computations will be way more faster compared to vpa.

We have just updated toolbox distribution/installer with the 'flintmax.m' already included.

Please download and use the latest toolbox version.

There is a quick way to make the built-in 'nchoosek()' work with toolbox. Create flintmax.m file in [toolbox_folder]\@char directory with following content:

function r = flintmax( classname )

if strcmpi('mp',classname)
        r = 2^ceil(mp.Digits() * mp('log2(10)'));
    else
        r = builtin('flintmax',classname);
    end
end

Restart MATLAB and test 'nchoosek()', e.g.:

>> mp.Digits(100);
>> x = nchoosek(mp(1000),50)

x = 

9460461017585217574825413104128279942327590136138287606176460370151247948488653144064

Toolbox doesn't include this function at the moment. Now I am considering to add it.

How do you use it? Just to compute binomial coefficient or to generate all combinations?

In our changelog we use 100 digits, but speed-up is implemented for any precision level.

Ok, we can make quadruple even faster, e.g. like this:

>> mp.Digits(34);M=500;A=(rand(M,'mp'))*10;

>> tic; expm(A); toc; % new
Elapsed time is 5.859282 seconds.

>> tic; expm(A); toc;  % old
Elapsed time is 26.809653 seconds.

Roughly ~5 times speed-up. 

Give me a minute, I will send you mpexpm.p with appropriate changes for quadruple.

Speed-up is valid for all precisions, including quadruple.  For quadruple speed is improved by ~2 times, e.g.:

>> mp.Digits(34);M=500;A=(rand(M,'mp'))*10;

>> tic; expm(A); toc; % new
Elapsed time is 12.147127 seconds.

>> tic; expm(A); toc;  % old
Elapsed time is 26.809653 seconds.

We can make it 4 times for quadruple is well, let me know if you are interested.

We have just included lsqnonneg into the newest toolbox version. Please re-download it from our webpage. Examples:

>> mp.Digits(34);
>> C = mp('[0.0372 0.2869;  0.6861  0.7071; 0.6233  0.6245; 0.6344 0.6170]');
>> d = mp('[0.8587; 0.1781; 0.0747; 0.8405]');
>> x = lsqnonneg(C,d)

x = 

                                           0    
        0.6929343971302933831938176511663673

>> mp.Digits(100);
>> C = mp('[0.0372 0.2869;  0.6861  0.7071; 0.6233  0.6245; 0.6344 0.6170]');
>> d = mp('[0.8587; 0.1781; 0.0747; 0.8405]');
>> x = lsqnonneg(C,d)

x = 

                                                                                  0    
        0.6929343971302933831938176511663670971062510...868165705163788676921766095

Options and multiple outputs are also supported.

Let me know how it works for your problem.

Thank you for confirmation!