Generates a new Permutation by randomly permuting blocks of size blocksize.
1. With Index range = [0,0], Block size = 3 and Permute within blocks is off, the permutation ((1,2,3),(4,5,6),(7,8,9)) is turned into one of six possible permutations, for example into ((4,5,6),(7,8,9),(1,2,3)). (The option No doublets will be ignored and the parentheses are only there to indicate the blocks.)
2. With Index range = [0,0], Block size = 3, Permute within blocks is on and No doublets is off, the permutation ((1,2,3),(4,5,6),(7,8,9)) might turn into ((5,4,6),(9,8,7),(3,1,2)).
3. With the same options as 2 but No doublets is on, the previously given outcome is forbidden because the last element of the first block (6) and the first element of the next block (9) are equal modulo 3 (the blocksize). A valid outcome might then be ((5,4,6),(8,9,7),(3,1,2)).
© djmw, January 5, 2011