Computational routine
eng
rndblk
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