System of DEs: Linear or Nonlinear? Competitive or Cooperative?

  • Thread starter Thread starter mathlete
  • Start date Start date
  • Tags Tags
    System
AI Thread Summary
The system of differential equations presented is non-linear due to the presence of the xy terms, despite Maple indicating otherwise for the first equation. The discussion highlights confusion regarding the classification of the system as competitive or cooperative, with participants noting that it is not a predator-prey model. Solutions to the equations tend to zero, but the specific classification remains unclear without further reference to textbook definitions. Clarification is provided that the linearity of the first equation does not apply to the system as a whole. Understanding the cooperative versus competitive nature requires consulting educational resources for accurate definitions.
mathlete
Messages
148
Reaction score
0
<br /> \frac{dx}{dt} = -5x+2xy
<br /> \frac{dy}{dt} = -4y+3xy<br />

Are these linear or nonlinear? I'm inclined to say non-linear but using maple it tells me it's linear ( odeadvisor(ode1, [linear]); returns [_linear] where ode1 is dx/dt).

Also, are they competitive or cooperative? I know it's not predator prey. I've graphed it and all solutions tend to 0, but I don't know what type that is (I can't find an explanation of cooperative/competitive anywhere on the internet)
 
Mathematics news on Phys.org
For the first question, they are definitely non-linear (xy terms). Maple is just wrong.

I can't answer the second question.
 
Apparently, you asked Maple whether the first equation is linear - which it is. With respect to the first equation alone, y = y(t) and it's clearly linear in the dependent variable x. The real question is whether the system of equations is linear - which it is not since the equations involve a product of the variables x and y.

For the second question you will have to resort to reading your textbook to know what the authors mean by cooperative vs. competitive.
 
OK thanks, I thought it had something to do with me just asking it about the one equation instead of the system.
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...
Fermat's Last Theorem has long been one of the most famous mathematical problems, and is now one of the most famous theorems. It simply states that the equation $$ a^n+b^n=c^n $$ has no solutions with positive integers if ##n>2.## It was named after Pierre de Fermat (1607-1665). The problem itself stems from the book Arithmetica by Diophantus of Alexandria. It gained popularity because Fermat noted in his copy "Cubum autem in duos cubos, aut quadratoquadratum in duos quadratoquadratos, et...
Thread 'Imaginary Pythagorus'
I posted this in the Lame Math thread, but it's got me thinking. Is there any validity to this? Or is it really just a mathematical trick? Naively, I see that i2 + plus 12 does equal zero2. But does this have a meaning? I know one can treat the imaginary number line as just another axis like the reals, but does that mean this does represent a triangle in the complex plane with a hypotenuse of length zero? Ibix offered a rendering of the diagram using what I assume is matrix* notation...
Back
Top