Introducing an if statement into time varying sin wave

Hello, I am having some trouble with using a for statement. I want to create the basics of a matlab code, that says if t<x, then matlab will use a sin function, but if t>=x, matlab is to use a function equal to zero. I have been able to create a basic code for a sin function going from 1 to 10 in steps of 0.1, but when i introduce a for statement so i can use and if and else statement it does not seem to work. I am sure this is a very basic matlab coding issue, but I need this simple basis in order to build up my coding for something else.

Anyways, the coding I have is:

clear all

Co=5000/60;

Cc=72; %number of cardiac cycles per minute

Tc=60/Cc; %period of cardiac cycle per second

Ts=(2/5)*Tc;%period of systole in seconds

q=(2*pi)/Ts;

I = (Co*Tc)/60*q;

t=[1:0.1:10];

if t>1

    A=I*sin(t);

else A=0;

end

plot(t,A)

I have tried including a for statement, but this also does not seem to work. Could anyone help me at all with this? It would be greatly appreciated! Thanks :D

Answer 1

[Mischa Kim]

Kelly, use something like

 Co = 5000/60;
 Cc = 72;            % number of cardiac cycles per minute
 Tc = 60/Cc;         % period of cardiac cycle per second
 Ts = (2/5)*Tc;      % period of systole in seconds
 q  = (2*pi)/Ts;
 I  = (Co*Tc)/60*q;

 t  = [1:0.1:10];
 A  = zeros(size(t)); % allocate memory for A
 for ii = 1:numel(t)  % start loop
    if t(ii)>3        % check ii-th element of t
        A(ii) = I*sin(t(ii));  % and assign ii-the element of A
    else
        A(ii) = 0;
    end
 end
 plot(t,A)

Not quite sure what you mean by x in t<x so I used a random time stamp in the if-else condition.