Prime reciprocal sum: Difference between revisions

=={{header|Pascal}}==

==={{header|Free Pascal}}===

Most time consuming is finding the next prime.

<syntaxhighlight lang=pascal>

program primeRezSum;

{$IFDEF FPC} {$MODE DELPHI}{$Optimization ON,ALL} {$ENDIF}

{$IFDEF WINDOWS}{$APPTYPE CONSOLE}{$ENDIF}

uses

sysutils,

gmp;

procedure OutStr(const s: AnsiString);

var

myString : AnsiString;

l : Integer;

begin

myString := copy(s,1,length(s));

l :=length(pChar(@s[1]));

setlength(myString,l);

IF l< 41 then

writeln(myString)

else

begin

myString[20]:= #0;

myString[21]:= #0;

writeln(pChar(@myString[1]),'...',pChar(@myString[l-19]),' (',l:6,' digits)');

end;

end;

var

nominator,denominator,tmp,tmpDemP,p : mpz_t;

s : AnsiString;

cnt : NativeUint;

begin

setlength(s,10000);

cnt := 1;

mpz_init(nominator);

mpz_init(tmp);

mpz_init(tmpDemP);

mpz_init_set_ui(denominator,1);

mpz_init_set_ui(p,2);

repeat

mpz_sub_ui(p,p,1);

mpz_nextprime(p,p);

write(cnt:3,' ');

repeat

mpz_mul(tmp,nominator,p);

mpz_add(tmp,tmp,denominator);

mpz_mul(tmpDemP,denominator,p);

if mpz_cmp(tmp,tmpDemP)< 0 then

BREAK;

mpz_nextprime (p,p);

until false;

mpz_get_str(pChar(@s[1]),10, p);

OutStr(s);

mpz_set(nominator,tmp);

mpz_mul(denominator,denominator,p);

//next smallest possible number denominator/delta

mpz_sub(tmp,denominator,nominator);

mpz_fdiv_q(p,denominator,tmp);

inc(cnt);

until cnt> 14;

end.</syntaxhighlight>

{{out|@TIO.RUN}}

<pre>

1 2

2 3

3 7

4 43

5 1811

6 654149

7 27082315109

8 153694141992520880899

9 337110658273917297268061074384231117039

10 8424197597064114319...13803869133407474043 ( 76 digits)

11 2030075381384823476...91313959045797597991 ( 150 digits)

12 2032370538147127284...21649394434192763213 ( 297 digits)

13 1274824659267207819...20708715953110886963 ( 592 digits)

14 4674902516513883824...65355869250350888941 ( 1180 digits)

Real time: 1.147 s User time: 1.093 s Sys. time: 0.046 s CPU share: 99.28 %</pre>