| Random_Gamma Routines | 
Unit
QESBPCSRandom
| Overloaded Variants | 
| Function Random_Gamma(const Shape: Extended): Extended; | 
| Function Random_Gamma(const Shape: Extended; RandomGenerator: TRandomGenFunction): Extended; | 
Declaration
Function Random_Gamma(const Shape: Extended): Extended;
Description
Adapted from Fortran 77 code from the book: Dagpunar, J. 'Principles of random variate generation' Clarendon Press, Oxford, 1988. ISBN 0-19-852202-9
Calls either random_gamma1 (Shape > 1.0)
OR random_exponential (Shape = 1.0)
OR random_gamma2 (Shape < 1.0).
| Parameters | 
| Shape | Shape Parameter of Distribution - must be Positive. | 
| RandomGenerator | Optional Function to use for Uniform Random Number Generator. If omitted, Delphi's Random function is used, and if this is done remember to call Randomize if you don't want repeated values. | 
Category
Arithmetic Routines for FloatsImplementation
 
| function Random_Gamma (const Shape: Extended): Extended;
begin
     Result := Random_Gamma (Shape, DelphiRandom);
End; | 
Declaration
Function Random_Gamma(const Shape: Extended; RandomGenerator: TRandomGenFunction): Extended;Implementation
 
| function Random_Gamma (const Shape: Extended;
     RandomGenerator: TRandomGenFunction): Extended;
begin
     if (Shape <= 0.0) then
          raise EMathError.Create (rsInvalidShape);
     if (Shape > 1.0) then
          Result := Random_Gamma1 (Shape, RandomGenerator)
     else if (Shape < 1.0) then
          Result := Random_Gamma2 (Shape, RandomGenerator)
     else
          Result := Random_Exponential (RandomGenerator);
End; | 
|  |