Kategorie: Wszystkie - solutions - stability

przez Christopher Voss 12 lat temu

438

Diff EQ

mapping out how to solve a differential equation based on certain parameters

Diff EQ

Diff EQ

Systems of diff EQs

eigen values
[a-lamda b c d-lamda]

tTake determinant, solve for lamda, plug in eigenvalue for general solution. If IVP plus in those values and solve for constants

2nd order

Subtopic
particular (LHS)
form based on function: Ae^t, At^2+Bt+C, Acosbt+Asinbt take derivative twice, plug back into RHS to solve for particular

variation of parameters

undetermined coefficients

homogeneous (RHS)
ar^2+br+c=0

repeated: y(t) = c1e^(r1t)+c2te^(r2t)

imaginary: y(t) = e^(at)(c1cosbt+c2sinbt)

real: y(h) = c1e^(r1t)+c2e^(r2t)

Nth order

LaPlace Transform
solve for Y(s), use tables, take inverse etc.
does it exist? (check for domain issues)
is it unique? (check derivative for domain issues)

1st order

integrating factor method
dy/dt + p(t)y = f(t) u = e^∫p(t)dt
Linear nonhomogenous
Find homogeneous and particular solutions
Linear + homogenous?
superposition principle
seperation of variables
(t)dt=(y)dy
directly integrate
isoclines, equilibrium, stability, concavity

application based (model)

competition model
(dR/dt) = R(ar-brR-crS)
tank problem
x'=(r_in)(c_in)-(r_out)(c_out)
Newton's law of cooling
(dT/dt) = k(M-T)
growth/decay
Q = Qo*e^kt