Exponential decay in MATLAB

Hi,

i need to calculate exponential decay of a radioisotope and store the data in a mat file, here is what i got so far...

I need use user inputs to calculate exponential decay, display when (numYears) the atomsLeft gets below the Threshold(T), and store all the values calculated into a mat file.

N = input('Enter the number of radioactive atoms we start with (integer): ');
HL = input('The lenght of half-life(in years): ');
T = input('The target threshold number of atoms (integer): ');

numYears = 0;

%Calculate the number of years for the decay to reach the target threshold.

for x = 1:HL    

atomsLeft = N.* 0.5.^(1:HL);

N = atomsLeft;

numYears = numYears + 1;

if T>N

      disp(['It took '  num2str(numYears) ' years to get below the treshold']);
  end
  end

save('mydata.mat', 'numYears'); %saves d in the data file 'mydata.mat'
save('mydata.mat', 'atomsLeft', '-append'); %adds t to the data file

I DK if its right

Outputs are rthe number of years it takes to decay below the threshold (T) And the atomsleft after numyears

And save the data in a mat file

Answer 1

[Walter Roberson]

One thing to fix:

atomsLeft = N.* 0.5.^(x);

It appears to me that there are other problems with the code, but you will need to indicate what your desired output is for us to be sure.

Answer 2

[Jan]

Outputs are rthe number of years it takes to decay below the threshold (T) And the atomsleft after numyears

And save the data in a mat file