Use reshape to convert a 1D array into a 2D arrays.
%%Reshape a column into a 2D array
myRandCol = rand(10000,1);
myRand2D = reshape(myRandCol,[100,100]);
%%Visualize
figure;imagesc(myRand2D);
Note: this example is slightly unrealistic, as it would make more sense to just generate the random number as a 2D matrix using
%%Generate Random Numbers as a 2D
myRand2D = rand(100,100)
However, that example isn't the in spirit of the question.
