SRL Archive - SRL Snippets

Thought I'd start a thread in the Snippets section for idea's/math related stuffs I've read from various books/articles/web pages/etc. and put them into simba syntax.

If you have a well though up theorem/function, I know there's plentiful choices out there in this world, so feel free to post them!

Collatz Theorem;

(*
  if the parameter, st, is odd then
    parameter will be multiplied by 3 then increased by 1.

  if the parameter, st, is even then
    parameter will be halved.

  Both if statments validate an increase in the result,
    which tracks how many calls to itself it takes for the parameter to reach 1.
*)

function CollatzRecursion(st : integer) : integer;
begin
  if (st = 1) then exit;

  if ((st mod 2) = 0) then
    st := (st div 2)
  else
    st := ((st * 3) + 1);
  writeln(st);
  result := CollatzRecursion(st) + 1;
end;

* Idea credit = java docs

result of the above, being used with a parameter of 3;

10
5
16
8
4
2
1
Successfully executed.

This shows what each value of the parameter, st, changes throughout the function.
The result of the function, tells the amount of numbers (as shown in code box) that were used. (in the example above, 7 is the amount/length of the result, when calling parameter, st, with an argument of 3)

{$i srl/srl.simba}

function BunnyMultiply(MaxDays: integer): TIntegerArray;
var
  i : integer;
begin
  SetLength(result, MaxDays);
  for i := 1 to MaxDays do
    result[i - 1] := (i - 1) * (i);
  DeleteValueInIntArray(result, 0);
end;

var
  amount, i : integer;
  arr : TIntegerArray;

begin
  amount := 10; // 9 days
  SetLength(arr, amount);
  arr := BunnyMultiply(amount);
  for i := 0 to high(arr) do
    Writeln('Day ' + IntToStr(i + 1) + ' bunny count = ' + IntToStr(arr[i]));
end.

* credit = java docs - will update better tomorrow

Will add in more as I find them. :)

Cheers,
Lj


Have quite a few Euler project snippets, but I know the point of the site isn't to hand out answers but to learn them.
So, I made a snippet in Lape, that is LIKE a question from their site;

(Sum n prime numbers, given any length of primes to find n (const PRIME_COUNT in code))

{$DEFINE STORE_PRIME_ARRAY}

// Find this many primes and sum them:
const PRIME_COUNT = 10; // 148933; Euler 2M

var count  : Integer = 1;
var target : Integer = 2;
var i_     : Integer = 3;
var index  : Integer = PRIME_COUNT;
var sum    : Int64 = 2;
{$IFDEF STORE_PRIME_ARRAY}
var Primes : array [0..(PRIME_COUNT - 1)] of Int64;
{$ENDIF}

function CheckIfEven(var input: Integer): Boolean;
begin
  Result := (input mod 2 = 0);
  if (Result) then input := input + 1;
end;

function isPrime(input: Integer): Boolean;
var
  i: Integer;
begin
  Result := False;
  i := 2;
  while (i <= Round(Sqrt(input))) do
    if (input mod i = 0) then
      Exit
    else
    begin
      Inc(i);
      CheckIfEven(i);
    end;
  Result := True;
end;

begin
  ClearDebug;
  while (count < index) do
  begin
    if (isPrime(i_)) then
    begin
      Inc(Count);
      target := i_;
      {$IFDEF STORE_PRIME_ARRAY}
      Primes[count - 1] := target;
      {$ENDIF}
      sum := sum + target;
    end;
    i_ := i_ + 2;
  end;
  {$IFDEF STORE_PRIME_ARRAY}
    Primes[0] := 2;
    Writeln(Primes);
  {$ENDIF}
  Writeln(Format('Last Prime (%d) @ index = %d', [target, index]));
end.

Factorials
-old removed!

new Factorials:

function fac(n : integer) : integer;
var
  i : integer;
begin
  result := 1;
  for i := 1 to n do
    result := result * i;
end;

From: Le Jingle
Factorials

var
  s : string;

function Factorial(n : integer): integer;
begin
  if (n = 0) then exit;
  s := s + '*' + IntToStr(n); // Cba #fence post
  result := Factorial(n - 1) * n;
end;

begin
  factorial(10);
  writeln(s);
end. 

This doesn't actually calculate the factorial of n, by the way. The result is always 0.

I love this! ;)
Some more debug examples for your last two would be nice. :)

Good job, good thread.

From: i luffs yeww
This doesn't actually calculate the factorial of n, by the way. The result is always 0.

opps good catch, base case should be == 1 :]
Cheers

edit lol, I got caught up string testing it, forgot that result should be the actual factorial of the called parameter n
>.<

From: Le Jingle
Factorials
-old removed!

new Factorials:

function fac(n : integer) : integer;
var
  i : integer;
begin
  result := 1;
  for i := 1 to n do
    result := result * i;
end;

Also you can calculate it as such:

Function Factorial(Var A: Integer): Extended;
Var
    X: Integer;
Begin
    Result := 1;
    For X := A Downto 1 Do
        Result := Result * X;
End;

function fac(n: Int64): Int64;
var
  i: Int64;
begin
  Result := 1;
  i := 1;
  while (i <= n) do
  begin
    Result := Result * i;
    i := i + 1;
  end;
end;

function IsPrime(input: Int64): Boolean;
var
  index: Int64;
begin
  Result := False;
  if (input < 2) then
    Exit;
  index := 2;
  while (index <= Sqrt(input)) do
  begin
    if (input mod index = 0) then
      Exit;
    index := index + 1;
  end;
  Result := True;
end;

don't think I have these 2 added yet:

function GCD(a, b: Integer): Integer;
var c: Integer;
begin
  while (a <> 0) do
  begin
    c := a;
    a := b mod a;
    b := c;
  end;
  Result := b;
end;

function isNotZero(n: Integer): Boolean;
begin
  Result := ((n or (n + 2147483647)) shr 31) and 1;
end;