Mertens function: Difference between revisions
Added Delphi example
m (Put Algol W in the correct place) |
MaiconSoft (talk | contribs) (Added Delphi example) |
||
Line 763:
M(n) is zero 92 times
M(n) crosses zero 59 times</pre>
=={{header|Delphi}}==
{{libheader| System.SysUtils}}
{{Trans|Go}}
<lang Delphi>
program Mertens_function;
{$APPTYPE CONSOLE}
uses
System.SysUtils;
type
TMertens = record
merts: TArray<Integer>;
zeros, crosses: Integer;
class function Mertens(_to: Integer): TMertens; static;
end;
{ TMertens }
class function TMertens.Mertens(_to: Integer): TMertens;
var
sum, zeros, crosses: Integer;
begin
if _to < 1 then
_to := 1;
sum := 0;
zeros := 0;
crosses := 0;
SetLength(Result.merts, _to + 1);
var primes := [2];
for var i := 1 to _to do
begin
var j := i;
var cp := 0;
var spf := false;
for var p in primes do
begin
if p > j then
Break;
if j mod p = 0 then
begin
j := j div p;
inc(cp);
end;
if j mod p = 0 then
begin
spf := true;
Break;
end;
end;
if (cp = 0) and (i > 2) then
begin
cp := 1;
SetLength(primes, Length(primes) + 1);
primes[High(primes)] := i;
end;
if not spf then
begin
if cp mod 2 = 0 then
inc(sum)
else
dec(sum);
end;
Result.merts[i] := sum;
if sum = 0 then
begin
inc(zeros);
if (i > 1) and (Result.merts[i - 1] <> 0) then
inc(crosses);
end;
end;
Result.zeros := zeros;
Result.crosses := crosses;
end;
begin
var m := TMertens.mertens(1000);
writeln('Mertens sequence - First 199 terms:');
for var i := 0 to 199 do
begin
if i = 0 then
begin
write(' ');
Continue;
end;
if i mod 20 = 0 then
writeln;
write(format(' %3d', [m.merts[i]]));
end;
writeln(#10#10'Equals zero ', m.zeros, ' times between 1 and 1000');
writeln(#10'Crosses zero ', m.crosses, ' times between 1 and 1000');
{$IFNDEF UNIX} readln; {$ENDIF}
end.</lang>
=={{header|F_Sharp|F#}}==
| |||