Timespan within Ode45

Hi there,

I'm writing code to try solve some differential equations.

function Output = example_3(m0,mEnd) % m0 = range of 1000 to 1500 and mEnd = range of 100 to 500 as an example

g0 = 9.81;
Isp = 390;
mdot = 5;


c = Isp.*g0;
mf = m0 - mEnd;
T = mdot .* Isp * g0;
tbo = mf./mdot;


T_Range =[0,tbo];
Y_01 = [0;0];

[tSol_1,YSol_1] = ode45(@deri_Y,T_Range,Y_01);

v_1 = YSol_1(:,1);
h_1 = YSol_1(:,2);

Output = [max(v_1), max(h_1)];


function dYdt = deri_Y(t,Y)

 v = Y(1);
 h = Y(2);
     
     dvdt = c.*mdot./(m0 - mdot.*t) - g0;
     dhdt = v;
     
     dYdt = zeros(size(Y));
     dYdt(1) = dvdt;
     dYdt(2) = dhdt;
     
end 

end

    

the function works for single inputs of m0 and mEnd but I would like the function to run for a range of m0 and mEnd values and because of this the value of tbo changes each time and I get an error saying:

"Unable to perform assignment because the left and right sides have a different number of elements.

Error in example_3/deri_Y (line 53)

dYdt(1) = dvdt;

Any help is greatly appreciated.

[darova]

Did you try for loop to get several solutions?

[Dylan Lawley]

I thought that might be how to solve it but dont know how to implament it properly.

Answer 1

[darova]

• change heade of a function

function dYdt = deri_Y(t,Y,m0)

• call the function

for m0 = [0.4 0.5 1]
    [tSol_1,YSol_1] = ode45(@(t,y) deri_Y(t,y,m0),T_Range,Y_01);
    line(tSol_1,YSol_1(:,1))
end

[Dylan Lawley]

thank you that helps a lot