MATLAB: When I generate a matrix with random numbers with the function rand, which is the order of generation

MATLABrandom number generator

I want to know if the matrix is generated vertically/columns or horizontally/rows.

Best Answer

Hi,
see this:
rng(25)
a = rand
rng(25)
b = rand(2,1)
rng(25)
x = rand(9,1)
rng(25)
y = rand(3,3)
which results in:
a =
      0.8701
b =
      0.8701
      0.5823
x =
      0.8701
      0.5823
      0.2788
      0.1859
      0.4111
      0.1174
      0.6850
      0.4376
      0.5562
y =
      0.8701    0.1859    0.6850
      0.5823    0.4111    0.4376
      0.2788    0.1174    0.5562
So we know it is generated in columns - which also follows the linear indexing rules of matlab:
x =
      0.8701
      0.5823
      0.2788
      0.1859
      0.4111
      0.1174
      0.6850
      0.4376
      0.5562
>> x1 = reshape(x,3,3)
x1 =
      0.8701    0.1859    0.6850
      0.5823    0.4111    0.4376
      0.2788    0.1174    0.5562
>> y
y =
      0.8701    0.1859    0.6850
      0.5823    0.4111    0.4376
      0.2788    0.1174    0.5562
Best regards
Stephan
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