its giving an error : Undefined function 'Length' for input arguments of type 'double'.

d= [10 30 60 100 500 800];
L_wallsdB =12;  % Penetration
Gmax=16;  % gain
Gs=20;    % sidelobe gain 
Gt=Gmax-Gs;

% Macropower i and Femtopwer j, Pj=Tx power of femto,  % in mW
Macropower=2000;    
Femtopower=100;

mpdb=10*log10(Macropower); % in dB
fpdb=10*log10(Femtopower); % in dB
no_of_macro=50;
no_of_femto=100;
wdb=2;  % penetrantion in dB
for i=1:Length(d);
    fprdb(d)=fpdb+Gt-(38.5+20*log10(d(i)));
    mprdb(d)=mpdb+Gt-(28+35*log10(d(i)));
end
fpr=10.^(fprdb./10);
mpr=10.^(mprdb./10);
w=10.^(wdb./10);
k=0:20:200;

for i=1:1:length(k);
    num(i)=mpr(3)+(Macropower-mpr(3)*0.1);
    den(i)=no_of_macro*mpr(5)+k(i)*fpr(1)+0.01;
    sir(i)=num(i)./den(i);
end
tp=3.84*log2(1+0.5*sir);
figure; plot(k,tp); hold on;
plot(k,tp,'ro')
axis tight;
grid on;
xlabel('number of femtocells');
ylabel('number of macrocells');
title('analyzing throghput ');

Answer 1

[madhan ravi]

for i=1:length(d);
%       ^------- should be lowercase

Note: Preallocate your variables .

Gives: