Undefined function or variable "t".

I try to run the code in the answer of: http://www.mathworks.com/matlabcentral/answers/259039-change-input-at-each-time-step-of-the-ode-solver-ode45

function yourIntegration
tResult = [];
xResult = [];
tStep = [7 14 21 28 35 42 49 56 63 70 77 84];
x0    = [64700 0 0.0033];
for index = 2:numel(tStep)
  % Integrate:
  beta = 0.43e-08 + (4.28e-08 - 0.43e-08) * exp(-0.20*t(index - 1))
  af   = @(t,x) f(t, x, beta);
  t    = tStep(index-1:index);
  [t, x] = ode45(af, t, x0);
    % Collect the results:
    tResult = cat(1, tResult, t);
    xResult = cat(1, xResult, x);
    % Final value of x is initial value for next step:
    x0 = x(end, :);
  end
function dx = f(t,x, beta)
dx = [3494-0.054*x(1)-beta*x(1)*x(3); ...
      beta*x(1)*x(3) - 0.41*x(2); ...
      50000*x(2) - 23*x(3)];

I encountered the error of

Undefined function or variable "t". Error in yourIntegration (line 8)   beta = 0.43e-08 + (4.28e-08 - 0.43e-08) * exp(-0.20*t(index - 1))

What should I do?

Answer 1

[Torsten]

Must read

beta = 0.43e-08 + (4.28e-08 - 0.43e-08) * exp(-0.20*tStep(index - 1))

Best wishes

Torsten.