| |
 | Posted by k-foley@onu.edu |  Permalink Reply |
|
k-foley@onu.edu 
| http://d.puremagic.com/issues/show_bug.cgi?id=3121
Summary: recurrence does not generate the correct numbers
Product: D
Version: 2.030
Platform: Other
OS/Version: Windows
Status: NEW
Keywords: patch, wrong-code
Severity: normal
Priority: P2
Component: Phobos
AssignedTo: nobody@puremagic.com
ReportedBy: k-foley@onu.edu
Original:
1943 struct Recurrence(alias fun, StateType, size_t stateSize)
1944 {
1945 StateType[stateSize] _state;
1946 size_t _n;
1947
1948 this(StateType[stateSize] initial) { _state = initial; }
1949
1950 void popFront()
1951 {
1952 _state[_n % stateSize] = binaryFun!(fun, "a", "n")(
1953 cycle(_state, _n), _n);
1954 ++_n;
1955 }
1956
1957 StateType front()
1958 {
1959 return _state[_n % stateSize];
1960 }
1961
1962 enum bool empty = false;
1963 }
Line 1953 should be "cycle(_state, _n), _n + stateSize);"
Otherwise, the factorial example will print an initial 1, followed infinitely by 0. Maybe the unittest should perform an assert rather than a print:
auto fact = recurrence!("n * a[n-1]")(1);
assert( equal(take(10, fact), [1, 1, 2, 2*3, 2*3*4, 2*3*4*5, 2*3*4*5*6,
2*3*4*5*6*7, 2*3*4*5*6*7*8, 2*3*4*5*6*7*8*9][]) );
--
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
|
