How to pass parameters?

Hi. I have to solve this differential equation

where

Here is Mischa Kim's code:

function piecewise()
x0    = 1;
tspan = linspace(0,3,1000);
[T,X] = ode45(@DE, tspan, x0);
plot(T,X)
end
%
function dX = DE(t,x)
A = log(2);
B = log(3);
C =1;
dX = -13.925*A*B*C*x + f(t);
end
%
function fval = f(t)
if     (t <= log(2))
    fval = exp(-t);
elseif (t > log(2)) && (t <= log(3))
    fval = 4;
else
    fval = 0;
end
end

How can I pass parameters A, B and C to the f function? I would like to write the if statement this way:

if     (t <= A)
      fval = exp(-Ct);
elseif (t > A) && (t <= B)
      fval = 4;

Answer 1

[James Tursa]

Not sure if this is what you want, but just pass them in:

dX = -13.925*A*B*C*x + f(t,A,B,C);
   :
function fval = f(t,A,B,C)
   :
  etc

If you want to pass them in from upstream of the ode45 call, then:

A = log(2);
B = log(3);
C = 1;
DEABC = @(t,x) DE(t,x,A,B,C);
[T,X] = ode45(DEABC, tspan, x0);
    :
function dX = DE(t,x,A,B,C)
dX = -13.925*A*B*C*x + f(t,A,B,C);
    :
function fval = f(t,A,B,C)
    :
   etc