function optZeros = ds_optzeros( n, opt )%optZeros = ds_optzeros( n, opt )%A helper function for the synthesizeNTF function of the Delta-Sigma Toolbox.%Returns the zeros which minimize the in-band noise power of %a delta-sigma modulator's NTF.if n==1    optZeros=0;elseif n==2    if opt==1	optZeros=sqrt(1/3);    else	optZeros=0;    endelseif n==3    optZeros=[sqrt(3/5) 0];elseif n==4    if opt==1	discr = sqrt(9./49-3./35);	tmp = 3./7;	optZeros=sqrt([tmp+discr tmp-discr]);    else	optZeros=[0 sqrt(5/7)];    endelseif n==5    discr = sqrt(25./81-5./21);    tmp = 5./9;    optZeros=sqrt([tmp+discr tmp-discr 0]);elseif n==6    if opt==1	optZeros=[0.93246935636220 0.66120925285410 0.23861957806940];    else	discr = sqrt(56.)/33;	tmp = 7./11;	optZeros=sqrt([0 tmp+discr tmp-discr]);    endelseif n==7    optZeros=[ 0.94910794020414 0.74153083158296 0.40584562459724 0];elseif n==8    optZeros=[ 0.96029008224551 0.79666675114317 0.52553208300091 0.18343409158171];elseif n==9    optZeros=[ 0.9685 0.8301 0.6222 0.3216 0 ];elseif n==10    optZeros=[ 0.9674 0.8847 0.6953 0.4217 0.1452 ];elseif n==11    optZeros=[ 0.9720 0.9010 0.7465 0.5252 0.1109 0 ];else    fprintf(1,'Optimized zeros for n > 8 are not available.\n');    return;end% Sort the zeros and replicate them.z = sort(optZeros);optZeros = zeros(n,1);m=1;if(rem(n,2)==1)    optZeros(1) = z(1);    z = z(2:length(z));    m=m+1;endfor(i=1:length(z))    optZeros(m)   =  z(i);    optZeros(m+1) = -z(i);    m = m+2;end