Hi !
I am a begginer in matlab and i am having some problems solving and ploting a system of differential equations with initial condition. The equation is defined as
r''(t) = Ft * r(t) + (0,0,m*g)
Ft = (1- llr(t)ll ) / llr(t)ll
where r(t) = (x(t), y(t), z(t)), llr(t)ll is lenght of vector r at time t and r(0) = (sin(45), 0, sin(45)), r'(0) = (0, 2, 0).
My code:
m=2;
g=9.8;
h=300;
syms x(t) y(t) z(t)
Ft = ((1/(x(t)^2+y(t)^2+z(t)^2)^(1/2))-1)*h;
eqns = [diff(x,t,2)== Ft*x, diff(y,t,2)==Ft*y, diff(z,t,2)==Ft*z+m*g];
cond = [y(0)==0, diff(y,0)==3, diff(x,0)==0, diff(z,0)==0, x(0)==(1/2)^(1/2), z(0)==(1/2)^(1/2)];
S = dsolve(eqns, cond);
fplot3(x(t),y(t),z(t))
Command window:
>> poskusi
Warning: Number of equations greater than number of indeterminates. Trying heuristics to reduce to square system.
> In symengine
In mupadengine/evalin_internal
In mupadengine/feval_internal
In dsolve>mupadDsolve (line 334)
In dsolve (line 203)
In poskusi (line 9)
Error using mupadengine/feval_internal
Unable to reduce to square system because the number of equations differs from the number of indeterminates.
Error in dsolve>mupadDsolve (line 334)
T = feval_internal(symengine,'symobj::dsolve',sys,x,options);
Error in dsolve (line 203)
sol = mupadDsolve(args, options);
Error in poskusi (line 9)
S = dsolve(eqns, cond);
Any suggestions for fixing it?
Thank you!
