MATLAB Answers

ode45 Not enough input arguments

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I am trying to model the differential equation of a low pass RC filter, using this equation: dVout/dt = (-1/RC)(Vout+Vin). I'm modeling Vin as a function, defined in the code below. Here is the ode function's code:
function dvdt = qprime(t,v)
global R
global C
R = 1/(500*2*pi*1*10.^(-6));
C = 1*10.^(-6);
function y = vi(z)
z = [0:0.01:2];
y = 5*sin(30*2*pi*z) + 0.1*sin(5400*2*pi*z);
end
dvdt = [(-1/(R*C))*v(1) + (-1/(R*C))*vi];
end
Here is the file I'm using to run it:
clear all
global R
global C
v0 = [0];
tspan = [0:0.01:2];
ode45(qprime69,tspan,v0)
I keep running into the issue of not having enough input arguments. Can someone help me figure out where I'm going wrong?

Accepted Answer

CARLOS RIASCOS
CARLOS RIASCOS on 4 Apr 2018
try this:
function dvdt = gprime(t,v)
global R
global C
V = 5*sin(30*2*pi*t) + 0.1*sin(5400*2*pi*t);
dvdt = (-1/(R*C))*v + (-1/(R*C))*V;
end
Then create another script like that, to resolve ODE.
clear all
clf
global R
global C
R = 1/(500*2*pi*1*10.^(-6));
C = 1*10.^(-6);
v0 = [0];
tspan = [0:0.001:2];
[t,x]=ode45(@gprime,tspan,v0);
plot(t,x)

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