MATLAB: Numerical solution of a system of ODE which is not in standard form

MATLABode

Hi

I' m wondering can MATLAB solve a system of ODE of these forms numerically?

H11*dydt+H12*dxdt=H13

H21*dydt+H22*dxdt=H23

I can change it to standard form but I have very large numbers which MATLAB has problem with it and I receive this massage:

Output truncated. Text exceeds maximum line length for Command Window display.

. I will upload my output. I want to solve these ODE numerically so I need the coefficient of all of terms in each eqaution. I utilized the collect cammand but it did not work. How cam I control and arrenge these large coeffisient. how can i determine each coeffisient correctly?

I would be gratefull if some one can help me.

thank you in advance

raha

this is some terms of output differential equation

(930441627500546658162730981425505183132667665707339718275447859267760748743794621

3848815439656366790278984387099311194969091496593187779728810864687259359515581251

8191929791546041229963635314657368394923219128924360408416905997843608302300038558

79197879071442125658901144………………………………………………0

0000000000000000000*Iass^8*IBss^5*Ipss^4 – 191746860148563438549216527115219808387369783

2286756806355856960741923824185970189……

Best Answer

It would likely help to have your code.

If you want more tractable numerical results, use the vpa function. The double function is also an option, however the arguments to it must not include any symbolic variables.

Related Solutions

MATLAB: How to simplify this complex equation using matlab

syms a b e l r 
Eq = 9*a^6*l - ((a^2*l*(b - 1)*(720*b^4*e^2 - 1440*b^3*e^2 + 720*b^2*e^2))/5 - (a^2*l*r*(b - 1)*(120*a^2*b^2*e - 120*a^2*b*e + 1440*b^4*e^2 + 120*b^4*e - 2880*b^3*e^2 - 360*b^3*e + 1440*b^2*e^2 + 240*b^2*e))/5)/r^2 - (9*a^7*l)/5 - a*l*(3*a + a*(a^2 - 1) - 12*a*e*(1/r - 1)*(b - 1)^2)^2 + 6*a^3*l*(3*a + a*(a^2 - 1) - 12*a*e*(1/r - 1)*(b - 1)^2) + b*l*(3*a + a*(a^2 - 1) - 12*a*e*(1/r - 1)*(b - 1)^2)^2 - a^3*l^3*((12*a^2)/l^2 + (2*a*(3*a + a*(a^2 - 1) - 12*a*e*(1/r - 1)*(b - 1)^2))/l^2) + b^3*l^3*((12*a^2)/l^2 + (2*a*(3*a + a*(a^2 - 1) - 12*a*e*(1/r - 1)*(b - 1)^2))/l^2) - 9*a^2*b^4*l + (9*a^2*b^5*l)/5 + a*l*(a*(a - 1)*(a - 2) + 12*a*e*(1/r - 1)*(b - 1)^2)^2 + (9*a^5*l*(a - 1)^2)/5 + 2*a^3*l*(a*(a - 1)*(a - 2) + 12*a*e*(1/r - 1)*(b - 1)^2)*(a - 1) - 6*a*b^2*l*(3*a + a*(a^2 - 1) - 12*a*e*(1/r - 1)*(b - 1)^2) - (a^2*l*(b - 1)*(5*a^4 + 120*a^2*b^2*e + 10*a^2*b^2 - 120*a^2*b*e - 20*a^2*b + 720*b^4*e^2 + 120*b^4*e + 9*b^4 - 1440*b^3*e^2 - 360*b^3*e - 36*b^3 + 720*b^2*e^2 + 240*b^2*e + 44*b^2 - 16*b + 4))/5
Eqs = simplify(Eq, 'Steps', 250)

Eqs =
(24*a^2*e*l*(b - 1)^2*(4*a - 2*b - 12*b*e + 12*b^2*e - 7*a^2 + 4*a^3 + b^2))/r - (4*a^2*l*(2*a^4 + 120*a^3*b^2*e - 240*a^3*b*e + 120*a^3*e - 6*a^3 - 210*a^2*b^2*e + 420*a^2*b*e - 210*a^2*e + 5*a^2 + 120*a*b^2*e - 240*a*b*e + 120*a*e + 180*b^4*e^2 + 30*b^4*e - 540*b^3*e^2 - 120*b^3*e + 540*b^2*e^2 + 150*b^2*e - 180*b*e^2 - 60*b*e - 1))/5 - (144*a^2*b*e^2*l*(b - 1)^3)/r^2

MATLAB: Value w.r.t to time

in,out %starting values
in =
       1     1
       3     2
       5     3
       7     4
       9     5
out =
       1     0
       2     0
       3     0
       4     0
       5     0
       6     0
       7     0
       8     0
       9     0
      10     0
mask = ismember(out(:,1),in(:,1));
out(mask,2)=in(:,2)
out =
       1     1
       2     0
       3     2
       4     0
       5     3
       6     0
       7     4
       8     0
       9     5
      10     0

Related Question