MATLAB: What is the fastest and most elegant way to calculate permutations of a vector of numbers

MATLABpermutationvector

First question Is this this the best way to calculate the permutation of a number (I don't want an array of digits)?
>> n = 123;
>> x = str2double(cellstr(perms(int2str(n))))
x =
   321
   312
   231
   213
   132
   123
I rather doubt it…
Second question If it is, what is the best way to calculate the permutation matrix of a number vector (assuming the number of digits is prescribed)?
For example (in this case the numbers from 111 to 999):
Permut = nan(6,889);
for number = 111:999
    counter = number-111+1;
    
    Permut(:,counter) = str2double(cellstr(perms(int2str(number))));
    
end
Or more generic:
numDigits = 3; 
nStart    = str2double(strrep(num2str(ones(    1,numDigits)), ' ', ''));
nFinal    = str2double(strrep(num2str(repmat(9,1,numDigits)), ' ', ''));
Permut    = nan(factorial(numDigits),nFinal-nStart+1);
for number = nStart:nFinal
    counter = number-nStart+1;
    
    Permut(:,counter) = str2double(cellstr(perms(int2str(number))));
    
end

Best Answer

Question 1:
perms(1:3) * [100; 10; 1]
Or the general case:
v = [2,5,4,8];
r = perms(v) * 10.^(numel(v)-1:-1:0).'
The multiple conversions by str2double, cellstr, and int2str are too indirect. If you want to work with numbers, stay at working with numbers.
If speed matters, replace perms by FEX: VChooseKO, which is about 10 times faster.
In your loop move the calculation of the power of 10 outside the loop.
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