Asked by Rebekah Kuehl
on 16 Jul 2019

For my project, I am calculating the half-life of an organism based on radioactive decay. My code is below. The problem I am experiencing is that he figure only has one point plotted. If someone could explain how to fix this so my entire function would be plotted, that would be greatly appreciated.

function Project

clc, clear

P=menu ('Please choose the element', 'Pm-145', 'Po-209', 'Ra-226', 'Ac-227', 'Am-243', 'Bk-247', 'Cf-251', 'C-14');

switch P %P=element found in sample through AMS

case 1 % Promethium-145

t=17.4;

case 2 % Polonium-209

t=102;

case 3 % Radium-226

t=1600;

case 4 % Actinium-227

t=21.77;

case 5 % Americium-243

t=7370;

case 6 % Berkelium-247

t=1380;

case 7 % Californium-251

t=898;

case 8 % Carbon-14

t=5730;

end

N=input ('Please enter the remaining percentage of substance: \n');

while N<=0 || N>=100 %N=percentage of element found through AMS

fprintf ('Incorrect input. Please try again. \n');

N=input ('Please enter the remaining percentage of substance: \n');

end

clc

age=(((log((N)/(100)))/(-0.693))*t);

fprintf ('The age of your organism is shown below: \n');

fprintf (' %s years',age);

n=length(N);

for i=1:n

plot(age(i), N(i), '*', 'MarkerSiz', 10)

xlim([0 inf])

ylim([0 100])

pause(.01)

hold all

xlabel(strcat('Years passed = ', num2str(age(i))))

ylabel(strcat('Percentage remaining =', num2str(N(i))))

title ('Radioactice Decay')

grid on

end

end

Thanks!

Answer by the cyclist
on 16 Jul 2019

Your variable N is a single value -- a scalar. (It is an array of length 1.) You then define n to be the length of that array. So n = 1.

Then, you plot in a for loop that goes from 1 to n. But that's from 1 to 1. So, you get one point.

David K.
on 16 Jul 2019

After you get the input for N, you could make it a vector with code like

N = 1:N;

Then if you want it to plot starting at the given percentage you could do

N = fliplr(N);

Rebekah Kuehl
on 16 Jul 2019

Where would I place the vector code that you posted?

David K.
on 16 Jul 2019

Right before you calculate age.

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## 6 Comments

## the cyclist (view profile)

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