Task

(Given an equal-probability generator of one of the integers 1 to 5
as dice5),   create dice7 that generates a pseudo-random integer from
1 to 7 in equal probability using only dice5 as a source of random
numbers,   and check the distribution for at least one million calls using the function created in   Simple Random Distribution Checker.


Implementation suggestion:
dice7 might call dice5 twice, re-call if four of the 25
combinations are given, otherwise split the other 21 combinations
into 7 groups of three, and return the group index from the rolls.

(Task adapted from an answer here)

proc D5 {} {expr {1 + int(5 * rand())}}
 
proc D7 {} {
    while 1 {
        set d55 [expr {5 * [D5] + [D5] - 6}]
        if {$d55 < 21} {
            return [expr {$d55 % 7 + 1}]
        }
    }
}