Subscript indices must either be real positive integers or logicals. where I have to change or update the code

clc;
clear all;
close all;
Transmitted_Message = 'SP22';
dec = double(Transmitted_Message); % text to ASCII (decimal)
p2 = 2.^(0:-1:-7); % 2^0,2^-1,.......,2^-7
B = mod(floor(p2'*dec),2); % decimal to binary conversion
% columns of B are bits of characters
x = reshape(B,1,numel(B));
disp('Transmitted message is:')
disp(Transmitted_Message)
disp('Binary information at Transmitter:');
disp(x);
F=1;
G=9;
%my id is 19-39319-1
br=(F+G+2)*200;
bp = 1/br;% bit period
%% representation of transmitting binary information as digital % signal
bit = [];
a0 = 12; % amplitude for binary bit 00
a1 = 16; % amplitude for binary bit 01
a2=20; % amplitude for binary bit 10
a3=24;% amplitude for binary bit 11
nt = 1000; % number of samples in a single bit period
for  n =linspace(1,2,length(x))
if x(n) == 0 &&  x(n+1)== 0 ;
se = a0*ones(1,nt);
elseif x(n) == 0 && x(n+1)== 1;
se = a1*ones(1,nt);
elseif x(n) == 1 && x(n+1)== 0;
se = a2*ones(1,nt);
else x(n) == 1 && x(n+1)== 1;
se = a3*ones(1,nt);
end
bit = [bit se];
end
 t = linspace(0, bp/nt, length(x)*bp-bp/nt));
plot (t,bit,'lineWidth',2);
ylabel('amplitude(volt)');
xlabel(' time(sec)');
title('Transmitting information as digital signal');

Answer 1

[Shnigdha Sharup]

remove linspace . write 2*bp/nt insted of bp/nt in t.

Answer 2

[Asaad Abboud Alkhalaf]

instead of for n =linspace(1,2,length(x))

use for n= 1:2:length(x) if you want vector with elements spaced by 2

or for n=1:length(x) if you want vector with ellemnts spaced by1

[Shnigdha Sharup]

Error using plot

Vectors must be the same length.

this problem occures while doing this