Editing Man or boy test (section)

==Knuth's example==
In [[ALGOL 60]]:
<syntaxhighlight lang="Pascal">
begin
  real procedure A(k, x1, x2, x3, x4, x5);
  value k; integer k;
  real x1, x2, x3, x4, x5;
  begin
    real procedure B;
    begin k := k - 1;
          B := A := A(k, B, x1, x2, x3, x4)
    end;
    if k ≤ 0 then A := x4 + x5 else B
  end;
  outreal(1, A(10, 1, -1, -1, 1, 0))
end
</syntaxhighlight>

This creates a tree of ''B'' call frames that refer to each other and to the containing ''A'' call frames, each of which has its own copy of ''k'' that changes every time the associated ''B'' is called. Trying to work it through on paper is probably fruitless, but for ''k''&nbsp;=&nbsp;10, the correct answer is −67, despite the fact that in the original article Knuth conjectured it to be −121. Even modern machines quickly run out of [[call stack|stack]] space for larger values of ''k'', which are tabulated below ({{OEIS2C|A132343}}).

{| class="wikitable" style="text-align:right"
! {{mvar|k}}
! {{tmath|A(k, 1, -1, -1, 1, 0)}}
|-
| 0
| 1
|-
| 1
| 0
|-
| 2
| −2
|-
| 3
| 0
|-
| 4
| 1
|-
| 5
| 0
|-
| 6
| 1
|-
| 7
| −1
|-
| 8
| −10
|-
| 9
| −30
|-
| 10
| −67
|-
| 11
| −138
|-
| 12
| −291
|-
| 13
| −642
|-
| 14
| {{val|−1,446}}
|-
| 15
| {{val|−3,250}}
|-
| 16
| {{val|−7,244}}
|-
| 17
| {{val|−16,065}}
|-
| 18
| {{val|−35,601}}
|-
| 19
| {{val|−78,985}}
|-
| 20
| {{val|−175,416}}
|-
| 21
| {{val|−389,695}}
|-
| 22
| {{val|−865,609}}
|-
| 23
| {{val|−1,922,362}}
|-
| 24
| {{val|−4,268,854}}
|-
| 25
| {{val|−9,479,595}}
|-
| 26
| {{val|−21,051,458}}
|}