Random generator

Library

Sources

Description

This block is a random wave generator: each output component takes piecewise constant random values. Every time an event is received on the input event port, the outputs take new independent random values. output port size is given by the size of A and B vectors

Dialog Box

Set Random generator block parameters
flag = 1 : Normal distribution A is mean and B deviation
A and B must be vector with equal sizes
seed is the seed of random number generator (integer$<$2**31)
flag	0
A	0
B	1
seed	7560437

• flag:0 or 1. 0 for uniform distribution on $[A,A+B ]$ and 1 for normal distribution.
• A: scalar
• B: scalar
• seed: seed value for a sequence of random number.

Default properties

• always active: no
• direct-feedthrough: no
• zero-crossing: no
• mode: no
• number/sizes of inputs: 0 /
• number/sizes of outputs: 1 / 1
• number/sizes of activation inputs: 1 / 1
• number/sizes of activation outputs: 0 /
• continuous-time state: no
• discrete-time state: yes
• name of computational function: rndblk

Interfacing function

scilab/macros/scicos_blocks/sources/RAND_f.sci

Computational function (type 0)

      subroutine rndblk(flag,nevprt,t,xd,x,nx,z,nz,tvec,ntvec,
     &     rpar,nrpar,ipar,nipar,u,nu,y,ny)
c     Copyright INRIA

c     Scicos block simulator
c
c     ipar(1) 
c            0 : uniform
c            1 : normal
c     rpar(1:ny)=mean
c     rpar(ny+1:2*ny)=deviation
c     rpar(2*ny+1)=dt 
c
      double precision t,xd(*),x(*),z(*),tvec(*),rpar(*),u(*),y(*)
      integer flag,nevprt,nx,nz,ntvec,nrpar,ipar(*)
      integer nipar,nu,ny

c
      double precision urand,sr,si,t1

      integer halt
      common /coshlt/ halt
c     
      if(flag.eq.1.or.flag.eq.6) then
      do 10 i=1,ny
         y(i)=rpar(i)+rpar(ny+i)*z(i+1)
 10   continue
      elseif(flag.eq.2.or.flag.eq.4) then
c     uniform
         if(ipar(1).eq.0) then
            iy=int(z(1))
            do 20 i=1,nz-1
               z(i+1)=urand(iy)
 20         continue
         else
            iy=int(z(1))
c     normal
            do 30 i=1,nz-1
 75            sr=2.0d+0*urand(iy)-1.0d+0
               si=2.0d+0*urand(iy)-1.0d+0
               t1 = sr*sr+si*si
               if (t1 .gt. 1.0d+0) go to 75
               z(i+1) = sr*sqrt(-2.0d+0*log(t1)/t1)
 30         continue
         endif
         z(1)=iy
c         if(ntvec.eq.1) tvec(1)=t+rpar(2*(nz-1)+1)
      endif
      return
      end