Largest difference between adjacent primes: Difference between revisions

</pre>

=={{header|XPL0}}==

<lang XPL0>def Size = 1_000_000_000/2; \sieve for odd numbers

int Prime, I, K;

char Flags;

int Limit, TenToThe, Max, Gap, I0, Prime0, Prime1;

[Flags:= MAlloc(Size+1); \(heap only provides 64 MB)

for I:= 0 to Size do \set flags all true

Flags(I):= true;

for I:= 0 to Size do

if Flags(I) then \found a prime

[Prime:= I+I+3;

K:= I+Prime; \first multiple to strike off

while K <= Size do \strike off all multiples

[Flags(K):= false;

K:= K+Prime;

];

];

Text(0, "Largest difference between adjacent primes under:

");

Limit:= 10;

for TenToThe:= 1 to 9 do

[Max:= 0; I0:= 0;

for I:= 0 to Limit/2-3 do

[if Flags(I) then \odd prime

[Gap:= I - I0;

if Gap > Max then

[Max:= Gap;

Prime0:= I0*2 + 3;

Prime1:= I *2 + 3;

];

I0:= I;

];

];

IntOut(0, Limit); Text(0, " is ");

IntOut(0, Prime1); Text(0, " - ");

IntOut(0, Prime0); Text(0, " = ");

IntOut(0, Max*2); CrLf(0);

Limit:= Limit*10;

];

]</lang>

{{out}}

<pre>

Largest difference between adjacent primes under:

10 is 5 - 3 = 2

100 is 97 - 89 = 8

1000 is 907 - 887 = 20

10000 is 9587 - 9551 = 36

100000 is 31469 - 31397 = 72

1000000 is 492227 - 492113 = 114

10000000 is 4652507 - 4652353 = 154

100000000 is 47326913 - 47326693 = 220

1000000000 is 436273291 - 436273009 = 282