Search Results
Search type | Search syntax |
---|---|
Tags | [tag] |
Exact | "words here" |
Author |
user:1234 user:me (yours) |
Score |
score:3 (3+) score:0 (none) |
Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
Views | views:250 |
Code | code:"if (foo != bar)" |
Sections |
title:apples body:"apples oranges" |
URL | url:"*.example.com" |
Saves | in:saves |
Status |
closed:yes duplicate:no migrated:no wiki:no |
Types |
is:question is:answer |
Exclude |
-[tag] -apples |
For more details on advanced search visit our help page |
Questions on the symbolic (DSolve, DifferentialRoot) and numerical (NDSolve) solutions of differential equations in Mathematica.
2
votes
1
answer
337
views
Partial DE and Mathematica book suggestion
I am studying Partial DE for my Master's.
I face a lot of difficulties in understanding them. It is the first time I am studying in my academic studies.
My main goal is to understand when systems are …
1
vote
1
answer
98
views
SI-model How to find the eigenvalues,solve numerical the system and Plot the answer [closed]
I have this system. I have found the equilibrium points and the Jacobian Matrix of each point. Now I am trying to calculate the eigenvalues and in the second step solve numerical the system.
r = 1; b …
3
votes
1
answer
271
views
Determine the equilibrium points of a predator-prey model?
I am trying to determine the equilibrium points
r=1;
b=1;
c=0.01;
μ=0.4;
deq1 = x'[t] == r*x[t] - b*x[t]^2 - c*x[t]*y[t] - 0.75*x[t]*y[t]/(a + x[t])
deq2 = y'[t] == μ*y[t] + 0.75*x[t]*y[t]/(a + x[t]) …
1
vote
1
answer
143
views
Plot in Improved Euler's Method problem [closed]
It is given the following problem:
$$x'=rx-bx^2-cxy-\frac{\beta xy}{\alpha+x}$$
$$y'=-\mu y+\frac{\beta xy}{\alpha+x}$$
With parameters $r=1,b=1,c=0.01, \mu=0.4,\alpha= 0.36$ and initial values $x(0)= …
1
vote
1
answer
73
views
Parametric3DPlot Problem [closed]
It is given the following problem:
$$X'=Z+(Y-\alpha)X$$
$$Y'=1-\beta Y-X^2$$
$$Z'=-X-\gamma Z$$
with initial conditions $(X(0),Y(0),Z(0)=(1,2,3)$.
Where
X: interest rate
Υ:investment demand
Z: price i …
5
votes
3
answers
518
views
Plot of Predator and Prey model problem
I am trying to solve the following problem.
I have the following constants and the differential equations.
r=1;
b=1;
c=0.01;
a=0.36;
a1=0.01;
a2=0.05;
c1=2;
c2=1;
μ=0.4;
m=0.01;
d=0.5;
e=15;
deq1 = x …
3
votes
1
answer
328
views
Simulation Lorenz83 Attractor
I tried to simulate the Lorenz83 Attractor that is defined by the following system of nonlinear ordinary differential equations:
\begin{eqnarray*}
\frac{dx}{dt}&=&-a x - y^2 - …
2
votes
1
answer
108
views
How to create direction field and phase line
Merry Christmas to all.
We have a problem we want to breed rainbowfish to sell to pet stores. We start with a nice big aquarium and 30 fish, half of them male, half of them female. We want to predict …
2
votes
1
answer
284
views
The characteristic equation for the eigenvalues of the Jacobian matrix
The mathematical model is
$$V'=\frac{I}{C}, V(0)=0$$
and
$$I'=\frac{-V}{L}-\frac{RI}{L}+\frac{V_β}{L}, I(0)=0$$
With I.C
$V_β=5 V, R=0.1Ω, L=4*10^{-9}H and C=0.5*10^{-9}F $
I have calculated and I hav …
2
votes
1
answer
66
views
Plot with manipulate
I want to use appropriately use the Manipulate command in conjunction with Plot, to construct animated graphics for the evolution of the solution. I have tried but i could not succed to solve it
$f(x) …
1
vote
1
answer
85
views
How to compare the numerical with the analytical solution of PDE?
Given the analytical solution
f[x_] := Exp[-x^2/2] (1 + 0.2*HermiteH[4, x] + 0.01*HermiteH[6, x])
n = 10;
A = Table[
1/(Sqrt[Pi] 2^m m!) Integrate[
f[x] HermiteH[m, x] Exp[x^2/2], {x, 0, 1}], …
2
votes
3
answers
137
views
How to plot a table of table?
soln = DSolve[y''[x] + y'[x] + y[x] == 0, y[x], x]
solTable =
Table[soln /. {C[1] -> i, C[2] -> j}, {i, -1, 1, 1}, {j, -1, 1, 1}]
Plot[solTable, {x, -2, 4}]
I am trying to generate the plot of the …
6
votes
2
answers
243
views
DSolve Problem with ODE
I am trying to solve the following differential equation
$$p'(t)=0.7p(t)(1-\frac{p(t)}{750})-20$$
and has an initial value $p(0)=30$
eqn = p'[t] == 0.7 p[t]*(1 - p[t]/750) - 20
sol = DSolve[{eqn, p[0] …
4
votes
1
answer
87
views
Studying hyperchaotic finance system
We study the paper "Dynamic analysis and control of a new hyperchaotic finance system"
It is given the following system
$$X'=Z+(Y-\alpha)X$$
$$Y'=1-\beta Y-X^2$$
$$Z'=-X-\gamma Z$$
with initial condit …
1
vote
1
answer
146
views
Plot Generalized Heat Equation
Given the following problem
$$u_{t}-\frac{v}{2}\cdot u_{xx}+\frac{v}{2}\cdot x^2 \cdot u(x)=0 $$
$$u(x,0)=f(x)$$
Where $ f(x)=y_1(x)+0.2y_4(x)+0.01y_6 (x) $
$y_n$ are the Eigenfunctions that defined …