I get different solutions from ODE45
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I tried to solve MIT's open courseware MatLab assigments. On the assigment they wanted plot different colors of lines depending on their value if it bigger than zero it would be red, it isn't it would black.
Here is the differential system and constans values.
My ODE45 function's code.
function dif_system = diferantial(t, x);
% Solver for the differantial system
% alphan(V), alphah(V), alpham(V), betan(V), betam(V), betah(V)
% these are the funciton scripts MIT gave us to use.
n = x(1);
m = x(2);
h = x(3);
V = x(4);
An = alphan(V); Bn = betan(V);
Am = alpham(V); Bm = betam(V);
Ah = alphah(V); Bh = betah(V);
% Membrane Capaticane
C = 1;
% Conductances
Gk = 36; % Potassium
Gna = 120; % Sodium
Gl = 0.3; % Leak channels
% Reversal potetias
Ek = -72; % Potassium
Ena = 55; % Sodium
El = -49.4; % Leak channels
dif_system = [(1-n)*An-(n*Bn);
(1-m)*Am-(m*Bm);
(1-h)*Ah-(h*Bh);
-C^-1*(Gk*n^4*(V-Ek)+Gna*m^3*h*(V-Ena)+Gl*(V-El))];
end
When i run the code my whole values are bigger than the zero(I shoved it down below).
Where i'm doing wong?
7 个评论
Firstly, yes i just upload the funciton scripti will give you the whole code down there. Secondly i don't understand the reason why my whole values are bigger than zero.
Qestion
Whole code
%% QUE_5
t_span = [0 20]; % 20ms
n = 0.5; m = 0.5; h = 0.5; V = -60;
conditions = [n m h V];
ySS = [n m h V];
hold on;
title("Approaching Steady State");
xlabel("Time (ms)"), ylabel("Transmembrane Voltage (V)");
for i=1:10
ySS(4) = ySS(4)+1;
[t, x] = ode45(@(t, x) diferantial(t, x), t_span, ySS);
if max(x(:,4)) > 0
plot(t, x(:,4), "Color", "red", "LineWidth", 1)
else
plot(t, x(:,4), "Color", "black", "LineWidth", 1)
end
end
hold off
function dif_system = diferantial(t, x);
n = x(1);
m = x(2);
h = x(3);
V = x(4);
An = alphan(V); Bn = betan(V);
Am = alpham(V); Bm = betam(V);
Ah = alphah(V); Bh = betah(V);
C = 1; Gk = 36; Gna = 120; Gl = 0.3;
Ek = -72; Ena = 55; El = -49.4;
dif_system = [(1-n)*An-(n*Bn);
(1-m)*Am-(m*Bm);
(1-h)*Ah-(h*Bh);
-C^-1*(Gk*n^4*(V-Ek)+Gna*m^3*h*(V-Ena)+Gl*(V-El))];
end
% returns the beta gating parameter for the m gate at voltage V
function b = betam(V)
b = 4*exp(-(V+60)/18);
end
% returns the beta gating parameter for the n gate at voltage V
function b = betan(V)
b = 0.125*exp(-(V+60)/80);
end
% returns the beta gating parameter for the h gate at voltage V
function b = betah(V)
b = 1./(exp(-(V+30)/10)+1);
end
% returns the alpha gating parameter for the h gate at voltage V
function a = alphah(V)
a = 0.07*exp(-0.05*(V+60));
end
% returns the alpha gating parameter for the m gate at voltage V
function a = alpham(V)
badIndices = find(abs(V+35)<1e-4);
goodIndices = find(abs(V+35)>=1e-4);
a(goodIndices) = -0.1*(V(goodIndices)+35)./(exp(-(V(goodIndices)+35)/10)-1);
if(max(size(badIndices))>0)
a(badIndices) = 1./(1-(V(badIndices)+35)/20);
end
end
% returns the alpha gating parameter for the n gate at voltage V
function a = alphan(V)
badIndices = find(abs(V+50)<1e-4);
goodIndices = find(abs(V+50)>=1e-4);
a(goodIndices) = -0.01*(V(goodIndices)+50)./(exp(-(V(goodIndices)+50)/10)-1);
if(max(size(badIndices))>0)
a(badIndices) = .1./(1-(V(badIndices)+50)/20);
end
end
I have attached the files that needed with function scritp file.
Emir Dönmez
2023-2-28
Emir Dönmez
2023-2-28
Torsten
2023-2-28
Usually, we cannot find modelling errors. We can only help with MATLAB syntax errors and sometimes with solver problems.
回答（1 个）
Walter Roberson
2023-2-28
0 个投票
Plotting the whole line in red if the voltage peak for the line is above 0 is what the question asks. It does not ask for the part of the line above 0 to be plotted in red.
Look for example at the wording about zooming in to see the threshold that separates the red lines from the black lines: that is definitely talking about red for the entire lines, not for line segments.
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