How to really speed up sine and cosine calculations

If you have ever written applications that require many sine and  cosine calculations over a short time you will have realized that things really start to slow down.

This is an old trick. But if you have never come across it, it really is worth using.

This version uses degrees not radians.


unit sin_Tool;

interface
const
  FULL_CIRCLE = 360;
  HALF_CIRCLE = 180;
//  TEN_CIRCLES = 3600;
function MySin(x:integer):real; overload;
function MySin(x:real):real; overload; //  allow both reals or integers

function MyCos(x:integer):real; overload;
function MyCos(x:real):real; overload;  //  allow both reals or integers

{ ===================================================== }
{ ===================================================== }
implementation

uses
   Math;
const
  MULTIPLIER = 10;
  NUM_ELEMENTS = FULL_CIRCLE * MULTIPLIER;
type
   tArcAnswers = array[0..NUM_ELEMENTS] of real;
var
   SinResults,
   CosResults:tArcAnswers;
{ =====================================================
function DegToRad(x:real):real; // OK... no need .. its in the math unit...
===================================================== }
procedure InitArcAnswers;
var
  c:integer;
begin
  for c := 0 to NUM_ELEMENTS do
  begin
    SinResults[c] := sin(DegToRad(c/ MULTIPLIER));
    CosResults[c] := cos(DegToRad(c/ MULTIPLIER));
  end;
  c := 1;
end;
{ ===================================================== }

function MySin(x:integer):real; overload;
begin
  while ( x > FULL_CIRCLE ) do
      x := x - FULL_CIRCLE;
  while ( x < 0 ) do
      x := x + FULL_CIRCLE;

  Result := SinResults[x * MULTIPLIER];
end;

function MySin(x:real):real; overload;
begin
  while ( x > FULL_CIRCLE ) do
      x := x - FULL_CIRCLE;
  while ( x < 0 ) do
      x := x + FULL_CIRCLE;
  Result := SinResults[round(x * MULTIPLIER)];
end;
{ ===================================================== }
function MyCos(x:integer):real; overload;
begin
  while ( x > FULL_CIRCLE ) do
      x := x - FULL_CIRCLE;
  while ( x < 0 ) do
      x := x + FULL_CIRCLE;
  Result := CosResults[x * MULTIPLIER];
end;

function MyCos(x:real):real; overload;
begin
  while ( x > FULL_CIRCLE ) do
      x := x - FULL_CIRCLE;
  while ( x < 0 ) do
      x := x + FULL_CIRCLE;
  Result := CosResults[round(x * MULTIPLIER)];
end;


{ ===================================================== }
{ ===================================================== }
initialization
begin
  InitArcAnswers;
end;


end.