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function [y]=RndInt(m,n,imin,imax)
// discrete uniform random number
//-------------------------------
// Copyright ENPC
y=rand(m,n,'uniform')
y=int(floor(y*(imax+1-imin)+ imin ));
endfunction
function [y]=RndDisc(m,n,x,p)
// discrete law random number
// sum p_i delta_{x_i}
//-------------------------------
p1=[0,p];p1=cumsum(p1);
y=rand(m,n,'uniform')
N=prod(size(x));
res=0*ones(m*n);
for i=1:N,z=0*ones(m*n,1),id=find( p1(i) <= y & y < p1(i+1) ),
z(id)=x(i)*ones(prod(size(id))),res=res+z;
end
y=matrix(res,m,n);
endfunction
function [y]=Binomial(m,n,pb,nb)
// Binomial law (p,N)
// P{X=n} = C_N^n p^n (1-p)^(N-n)
//----------------------------------
res=[];
// we use blocks of size 100 to avoid overflows
ntir=100;
ntirc=ntir;
y=rand(ntir,nb,'uniform');
indy= find( y < pb);
y=0*ones(y);
y(indy)=1;
y=sum(y,'c')
res=[res;y];
while ( ntirc < m*n )
y=rand(ntir,nb,'uniform');
indy= find(y< pb);
y=0*ones(y);
y(indy)=1;
y=sum(y,'c')
res=[res;y];
ntirc=ntirc+ntir;
end
y=matrix(res(1:m*n),m,n);
endfunction
function [y]=Geom(m,n,p)
// P(0)= 0 P(i) = p*(1-p)^{n-1} P(inf)=0
// E = 1/p ; sig2= (1-p)/p^2
//--------------------------------------
if p >= 1 then write(%io(2),'p must be < 1');end
y=0*ones(m,n)
for i=1:m*n,
samples=1
z=rand(1,1,'uniform');
while( z < 1-p) ,z=rand(1,1,'uniform'); samples=samples+1;end
y(i)= samples;
end
y=matrix(y,m,n)
endfunction
function [y]=Poisson(m,n,pmean)
// P{n} = exp(-lambda)lambda^n/n!
// pmean =lambda
//----------------------------
y=0*ones(m,n)
bound= exp(-pmean);
for i=1:m*n,
count=0
lprod=1
while( lprod >= bound), lprod=lprod*rand(1,1,'uniform');
count=count+1;end
y(i)=count-1;
end
y=matrix(y,m,n)
endfunction
function [y]=Exp(m,n,lambda)
// lambda exp(-lambda x) x>=0
// ---------------------------
y=(-1/lambda)* log(rand(m,n,'uniform'));
endfunction
function [y]=Weibull(m,n,Alpha,Beta)
//-------------------------------
y=rand(m,n,'uniform')
y= (Beta*( - log(1-y)))^(1/Alpha)
endfunction
function [y]=HyperGeom(m,n,Mean,var)
//-------------------------------
z = var / (Mean * Mean);
pP = 0.5 * (1.0 - sqrt((z - 1.0) / ( z + 1.0 )));
y=rand(m,n,'uniform')
zz=find( y > pP) ;
y=pP*ones(y);
y(zz) = (1-pP)*ones(zz);
y1=rand(m,n,'uniform')
y=-Mean * log(y1) ./ (2.0 * y) ;
endfunction
function [y]=Erlang(m,n,pMean,pVariance)
//-------------------------------
k = int( (pMean * pMean ) / pVariance + 0.5 );
if (k <= 0) then k=1;end
a = k / pMean;
// we use blocks of size 100 to avoid overflows
res=[];
ntir=100;
ntirc=ntir;
y=rand(ntir,k,'uniform');
y= -log(prod(y,'r'))/a;
res=[res;y];
while ( ntirc < m*n )
y=rand(ntir,k,'uniform');
y= -log(prod(y,'r'))/a;
res=[res;y];
ntirc=ntirc+ntir;
end
y=matrix(res(1:m*n),m,n);
endfunction
function [y]=RndPerm(n)
//-------------------------------
// a uniform random permutation of (1:n)
y=rand(1,n,'uniform')
[us,z]=sort(y);
endfunction
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