How many combination will appear

A=[1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49];
B = nchoosek(A, 7)

Answer 1

[Roger Stafford]

I hope you have a lot of memory available to matlab! B will be of size 85900584 by 7. That is, there will be 49!/7!/42! combinations.

[Roger Stafford]

It occurs to me that what you might have wanted was to generate, say, N random equally likely combinations of seven numbers chosen from among the forty-nine, where N is very much less than the number I quoted above. If so, you could do this:

C = zeros(N,7);
for k = 1:N
  C(k,:) = sort(randperm(49,7));
end

[dhmhtrhs]

i don't know good english, i want write a example the who are executable for i see doing

[Roger Stafford]

I’m not sure I completely understand what you are saying, Dhmhtrhs. I ran the above code on my computer’s version of Matlab, and got the following random result. I chose N = 10, so C has ten rows with each one containing a combination of seven random numbers chosen from among the numbers from one to forty-nine. You are probably interested in more than ten random samples, but probably far less than 49!/7!/42! = 85,900,584.

disp(C)

     1    10    14    16    25    32    46
    19    21    25    28    30    40    47
     7    10    12    25    29    31    35
     1    10    12    26    32    38    39
    22    24    33    34    35    37    47
    10    24    25    28    39    41    43
     4     6    23    25    33    37    48
     7    11    13    16    19    26    28
     7    17    20    26    30    35    37
     6     8    17    23    28    34    36