Of course not. for example:
function [ds3out, out3, out2, out1, fb] = ds31(rst, insamp, out3, out2, out1, fb)
if (rst == 0)
out1(2) = insamp/16 - fb(1)/16 + out1(1);
out2(2) = out1(1) - fb(1)/4 - out3(1)/128 + out2(1);
out3(2) = out2(1) - fb(1)*(1/2+1/4) + out3(1);
quantized = quantizer(out3(2));
ds3out=quantized;
%update the ds3 state
unquantized = unquantizer(quantized);
out1(1) = out1(2);
out2(1) = out2(2);
out3(1) = out3(2);
fb(1) = unquantized;
else
out1(1:2)=0; ds3out=0; out2(1:2)=0; out3(1:2)=0;
end;
function quantizer_out = quantizer(insamp)
% quantizer for delta-sigma modulator
qlevel0 = 30720;
qlevel1 = 26624;
qlevel2 = 22528;
qlevel3 = 18432;
qlevel4 = 14336;
qlevel5 = 10244;
qlevel6 = 6144;
qlevel7 = 2048;
qlevel8 = -2048;
qlevel9 = -6144;
qlevel10 = -10244;
qlevel11 = -14336;
qlevel12 = -18432;
qlevel13 = -22528;
qlevel14 = -26624;
qlevel15 = -30720;
if(insamp > qlevel0)
quantizer_out=16;
end;
if((qlevel0 >= insamp) & (insamp > qlevel1))
quantizer_out=15;
end;
if((qlevel1 >= insamp) & (insamp > qlevel2))
quantizer_out=14;
end;
if((qlevel2 >= insamp) & (insamp > qlevel3))
quantizer_out=13;
end;
if((qlevel3 >= insamp) & (insamp > qlevel4))
quantizer_out=12;
end;
if((qlevel4 >= insamp) & (insamp > qlevel5))
quantizer_out=11;
end;
if((qlevel5 >= insamp) & (insamp > qlevel6))
quantizer_out=10;
end;
if((qlevel6 >= insamp) & (insamp > qlevel7))
quantizer_out=9;
end;
if((qlevel7 >= insamp) & (insamp > qlevel8))
quantizer_out=8;
end;
if((qlevel8 >= insamp) & (insamp > qlevel9))
quantizer_out=7;
end;
if((qlevel9 >= insamp) & (insamp > qlevel10))
quantizer_out=6;
end;
if((qlevel10 >= insamp) & (insamp > qlevel11))
quantizer_out=5;
end;
if((qlevel11 >= insamp) & (insamp > qlevel12))
quantizer_out=4;
end;
if((qlevel12 >= insamp) & (insamp > qlevel13))
quantizer_out=3;
end;
if((qlevel13 >= insamp) & (insamp > qlevel14))
quantizer_out=2;
end;
if((qlevel14 >= insamp) & (insamp > qlevel15))
quantizer_out=1;
end;
if(qlevel15 >= insamp)
quantizer_out=0;
end;
function unquantizer_out = unquantizer(insamp)
% unquantizer for delta-sigma modulator
qlevel0 = 32768;
qlevel1 = 28672;
qlevel2 = 24576;
qlevel3 = 20480;
qlevel4 = 16384;
qlevel5 = 12288;
qlevel6 = 8192;
qlevel7 = 4096;
qlevel8 = 0;
qlevel9 = -4096;
qlevel10 = -8192;
qlevel11 = -12288;
qlevel12 = -16384;
qlevel13 = -20480;
qlevel14 = -24576;
qlevel15 = -28672;
qlevel16 = -32768;
if(insamp == 16)
unquantizer_out=qlevel0;
end;
if(insamp == 15)
unquantizer_out=qlevel1;
end;
if(insamp == 14)
unquantizer_out=qlevel2;
end;
if(insamp == 13)
unquantizer_out=qlevel3;
end;
if(insamp == 12)
unquantizer_out=qlevel4;
end;
if(insamp == 11)
unquantizer_out=qlevel5;
end;
if(insamp == 10)
unquantizer_out=qlevel6;
end;
if(insamp == 9)
unquantizer_out=qlevel7;
end;
if(insamp == 8)
unquantizer_out=qlevel8;
end;
if(insamp == 7)
unquantizer_out=qlevel9;
end;
if(insamp == 6)
unquantizer_out=qlevel10;
end;
if(insamp == 5)
unquantizer_out=qlevel11;
end;
if(insamp == 4)
unquantizer_out=qlevel12;
end;
if(insamp == 3)
unquantizer_out=qlevel13;
end;
if(insamp == 2)
unquantizer_out=qlevel14;
end;
if(insamp == 1)
unquantizer_out=qlevel15;
end;
if(insamp == 0)
unquantizer_out=qlevel16;
end;