Need help creating a loop

The concentration of a drug in the body, Cp, can be modeled by the equation:

where Dg is the dosage administered in mg, Vd is the volume of the distribution in liters, ka is the absorption rate of the drug into the body in 1/hour, ke is the body's elimination rate of the drug from the body also in 1/hr, and t is the time in hours since the drug was administered.

Create a script file that uses a for loop to calculate the concentration of two, 12 hour doses of a drug over a 24 hour period every 6 minutes (0.1 hours) given that Dg=100 mg, Vd=50 L, ka=1.8/hr, and ke=0.1/hr. Create a vector named Cp that stores all concentration values over the entire 24 hour period. You will need to vectorize your code (create a vector, one element at a time with each pass through the loop). It may help to use a counting variable to go through your loop and that could look something like this:

Cp(count) = ....

To properly account for the two seperate doses, you need to set up your equations as follows:

If t <= 12 hours use this equation:

If t > 12 hours and <= 24 hours, use this equation:

Generate a fully formatted plot for Cp over 24 hours time period.

Note: You must use the time vector as your range over which you are looping your iterator (loop) variable. Use a counting variable which you increment at the end of the loop to vectorize Cp.

I use this code but keep getting it wrong. I don't know what to do.

Dg = 100;

Vd = 50;

ka = 1.8;

ke = 0.1;

t = 0.1:.1:24;

for k = 1:length(t)

if t(k) <= 12

Cp(k) = (Dg/Vd)/(ka/(ka-ke))*(exp((-ke).*t) - exp((-ka).*t))

else

Cp(k) = (Dg/Vd)/(ka/(ka-ke))*(exp((-ke).*t) - exp((-ka).*t)) + (Dg/Vd)/(ka/(ka-ke))*(exp((-ke).*(t-12)) - exp((-ka).*(t-12)))

end

end

[Angshuman Podder]

This script seems to run.

[Giovanni Principato]

I submitted the wrong one try this one

Answer 1

[Angshuman Podder]

Replace t with t(k).

clc
clear

Dg = 100; 
Vd = 50;
ka = 1.8;
ke = 0.1;
t = 0.1:.1:24;

Cp = zeros(1,length(t));

for k = 1:length(t) 
    if t(k) <= 12 
        Cp(k) = (Dg/Vd)/(ka/(ka-ke))*(exp((-ke)*t(k)) - exp((-ka)*t(k)));
    else
        Cp(k) = (Dg/Vd)/(ka/(ka-ke))*(exp((-ke)*t(k)) - exp((-ka)*t(k))) + (Dg/Vd)/(ka/(ka-ke))*(exp((-ke)*(t(k)-12)) - exp((-ka)*(t(k)-12)));
    end  
 
end

[Angshuman Podder]

Your previous code was also right.