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MATLAB Octave integral computation help

  1. Apr 20, 2017 #1

    I'm having some trouble with my octave coding and would appreciate any input on where the issue lies.
    The coding is as follows:

    Code (Matlab M):

    age = [0:1:100];                            %this is the age matrix, represented by a
    time = [0:1:100];                           %this is the time matrix, represented by t

    population = zeros(101,101);

    for a = 1:101;
      population(a,1) = 0.5;                    %this is the initial population
      B(a) = (1./(2.*a));                          %this is the birthing probability at age (a)
    for t = 1:100
      for a = 2:101
        population(1,t+1) = cumtrapz(B(a));     %this is the birth rate
       population(a,t+1) = population(a-1,t);    %this is the interation process

    <Moderator's note: code tags added. Please use them when posting code.>

    The issue I'm having lies in the population matrix computation; the cumtrapz integration is not recognizing the step process and all outputs from t = 2:101 in the population matrix are zeros. I would again appreciate any help to understand where the issue lies.

    Thank You,
    Jacob M.
    Last edited by a moderator: Apr 21, 2017
  2. jcsd
  3. Apr 21, 2017 #2


    User Avatar

    Staff: Mentor

    You are passing a single element to cumtrapz, not an array.

    Explaining what you are trying to do (with equations) would help.
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