Write a script which produces a table which approximates half-life decay. P(t) =

Question

Write a script which produces a table which approximates half-life decay. P(t) = P_0(1/2)^t/t_1/2 Your program should take two inputs: (a) the initial population (P_0) (b) the half-life (t_1/2) in years. Your program should then produce a table (see format below) which gives the decaying population and corresponding time values until the population reaches 1. Your function should allow for repeated operation until a terminating condition (such as negative starting population) is specified. Enter the starting population (billions): 20 Enter the half-life of the material (years): 5

Explanation / Answer

#save as decay.m
#prompt user to enter starting population
p0=input('Enter the starting population(billions):');
#prompt user to enter t 1/2
tHalf=input('Enter the half-life of the material(years):');

#set time,t=0
t=0;
#set repeat to true
repeat=true;
#calculate population
population=p0*(0.5^(t/tHalf));
#print heading
fprintf('%-15s %-15s ','Time(years)','Pop(billions)');
fprintf('%-15s %-15s ','=====','==========');
fprintf('%-15d %-15.2f ',t,population);
#repeat until the repeat condition is true
while repeat

#set time,t=t5
t=t+5;  
#calculate population
population=p0*(0.5^(t/tHalf));

#check population is >1
if population>1
    fprintf('%-15d %-15.2f ',t,population);
else
#otherwise set repeat=false
    repeat=false;
end

   #end while loop
end

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Sample Output

>>Enter the starting population(billions):20
Enter the half-life of the material(years):5
Time(years)     Pop(billions)
=====           ==========
0               20.00
5               10.00
10              5.00
15              2.50
20              1.25

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