- you are using symbolic variables. ode45 needs function or function handle
- your no function depends on several variables (a lot), ode45 works only with one independent variable (ordinary differential equation)
ODE error message "Error using exist The first input to exist must be a string scalar or character vector"
11 visualizaciones (últimos 30 días)
Mostrar comentarios más antiguos
this is my code
syms no(k1,k2,k3,k_1,k_2,k_3,o2,n2,o,h2o,oh,h,t)
n=(k1*o*n2+k_2*no*o+k_3*no*h)/(k_1*no+k2*o2+k3*oh);
eqn1=k1*o*n2-k_1*no*n+k2*n*o2-k_2*no*o+k3*n*oh-k_3*no*h;
fin = diff(no,t)==eqn1;
tspan = [0 10];
i=[0 0];
ra=ode45(fin,tspan,i)
2 comentarios
darova
el 29 de Mayo de 2020
Can you attach original equations?
Respuestas (2)
darova
el 29 de Mayo de 2020
Try this way: prepare function handle for ode45 solver
fin = @(t,no) k1*o*n2-k_1*no*((k1*o*n2+k_2*no*o+k_3*no*h)/(k_1*no+k2*o2+k3*oh))+k2*((k1*o*n2+k_2*no*o+k_3*no*h)/(k_1*no+k2*o2+k3*oh))*o2-k_2*no*o+k3*((k1*o*n2+k_2*no*o+k_3*no*h)/(k_1*no+k2*o2+k3*oh))*oh-k_3*no*h;
[t,no] = ode45(fin,[0 1e-7],0);
plot(t,no)
0 comentarios
Abdelrahman Eldaly
el 29 de Mayo de 2020
Editada: Abdelrahman Eldaly
el 29 de Mayo de 2020
3 comentarios
darova
el 29 de Mayo de 2020
The only idea i have is to separate this long expression into two parts. Because it's hard to check if it's correct or not
% fin = @(t,no) k1*o*n2-k_1*no*((k1*o*n2+k_2*no*o+k_3*no*h)/(k_1*no+k2*o2+k3*oh))+k2*((k1*o*n2+k_2*no*o+k_3*no*h)/(k_1*no+k2*o2+k3*oh))*o2-k_2*no*o+k3*((k1*o*n2+k_2*no*o+k_3*no*h)/(k_1*no+k2*o2+k3*oh))*oh-k_3*no*h;
N = @(no) (...)/(...);
fin = @(t,no) k1*o*n2 - k_1*no*N(no) + ...
Ver también
Categorías
Más información sobre Symbolic Math Toolbox en Help Center y File Exchange.
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!