nb_rnd.prg

矩阵求逆算法程序

/*----------------------------------------------------------------

          NB_RND.PRG     FUNCTION

CLAIM:    {This isn't gold, but...}
          
          Returns a psuedo-random number between
          zero (inclusive) and one (exclusive).

DESIGNED BY:
          
          Nathan C. Baker
          HC 83 Box 49
          Ellenboro, West Virginia
          26346 U.S.A.

          Phone: [phone]
          CIS: 73514,1031

WRITTEN IN:
          
          CA-Clipper 5.x
          (Should work with all six flavors)

TERMS:

          This function (source code, object, and executable) are
          placed in the public domain.  As PUBLIC DOMAIN software,
          it may be used by anyone for any purpose without fee or
          charge of any kind from me.  If you can make money from
          it, please do.  If you want to take credit for it, be my
          guest.  I developed the main algorithm in the Spring of
          1993 in response to Clipper's lack of such a function.
          Uploaded to CompuServe on December 27, 1993.  Object
          compiled using CA-Clipper 5.2c.  Please feel free to
          disperse these files to other online services, bulletin
          board systems (BBS), or library collections.  I wish
          you the best of luck converting the algorithm to other
          languages and/or platforms.

-----------------------------------------------------------------*/

#define Pi 3.14159265358979   //One natural number.
#define Epsilon Exp(1)        //Another natural number.


FUNCTION NB_RND()

LOCAL nA, nB, nC, nD
STATIC nClock := 0
STATIC nSeed := 0

IF nClock == 0
     nClock := nSeed := Seconds()
ENDIF
IF nClock == Seconds()
     nSeed := nSeed * Pi/Epsilon
ELSE
     nClock := nSeed := Seconds()
ENDIF
IF nSeed == 0                 //When the clock strikes midnight,
     nSeed := Pi + Epsilon    //the mouse takes another byte.
ENDIF


nA := (nSeed * 100) / (Pi - Int(Pi) + Epsilon - Int(Epsilon))
nB := (nA - Int(nA)) / nSeed
nC := nB + 1 / If(nB == 0, Pi + Epsilon, nB)
nD := Exp(nB + Log(nC)) - Int(Exp(nB + Log(nC)))

RETURN nD

/*--------------------------------------------------------*/
// This function takes advantage of the error introduced
// when subtracting the Int(x) from x as illustrated below:
//
// 9110939.05395725200000000
// 0000000.05395725183188915
//
// The first number above is x and the second number is x - Int(x).
//
/*------------------------------------------------------*/
// All values obtained with CA-Clipper 5.2c running on a
// non-Intel 386sx with no co-processor (saving money for
// a DEC Alpha machine because Santa didn't bring it <G>).
//
/*THE END*/