0
votes
0answers
16 views

Matlab: solve system of equations using substitution

Suppose I want to solve a system of equations $F(x)$ which is shown as below: $x_1^3+1=0$ $x_1+x_2=0$ I want to substitute $x$ by $x_1=2y_1, x_2=3y_2$. Then the original system is transformed to ...
1
vote
0answers
43 views

Time needed to algebraically solve system of $15$ nonlinear equations with parameters

How long can I expect it will take to algebraically solve a system of $15$ nonlinear equations (without any numbers, only parameters), if I feed it into a computing software? I'm asking for symbolic ...
0
votes
1answer
51 views

How to solve these two differential equation?

I try to solve these two difference equation ; $$ \frac{dq}{dz} = -j\left(b_1q - kp\right),\\ \frac{dp}{dz} = -j\left(b_2p - kq\right) $$ where $j$ stands for $\sqrt{-1}$, and $b_1$ ,$b_2$ and k are ...
0
votes
0answers
32 views

Solving solely continuous system of ode's with matlab

I'm working with the numerical integration of the system of differential equations, $\dot{x}=f(x)$ with the vectorfield, $f(x)$ being solely continuous. Examples of the systems which I'm working on ...
4
votes
1answer
66 views

Due to numerical inaccuracy, the solution of a boundary value problems becomes negative

I treat a toy example to get my point across. In reality I have to deal with a much more complex model. Let us consider a one dimensional boundary value problem using the bvp5c solver in Matlab. Two ...
0
votes
0answers
57 views

SIR models - help!

I am doing a project on the spread of infectious diseases and I have chosen to model this spread by using the SIR model - (susceptibles, infectious, recovered). I have to insert data into this model ...
1
vote
0answers
82 views

Solving a Large band system using Gauss-Seidel Iteration

Sorry for my english. I have to solve the following band system using Gauss-seidel iteration program in matlab. $$ \begin{array}{cccccc} 12x_1&-2x_2&+x_3&&&=&5\\ ...
0
votes
2answers
38 views

Ordinary differential equations with signed first derivative

Consider the following coupled set of ordinary diferential equations: \begin{align} (K_{pa}+K_r)y_1(t)-K_ry_2(t)+C_0\operatorname{sign}(\dot{y}_1(t))\lvert\dot{y}_1(t)\rvert^\alpha &= ...
0
votes
1answer
82 views

Solving a nonlinear system of differential equations in MATLAB or Mathematica

Is it possible to solve the system $$\dot{W}=A\left(k-\frac{M}{W}\right)$$ $$\dot{M}=B\left(k-\frac{M}{W}\right)$$ with initial conditions $$W(0)=w_0$$ $$M(0)=m_0$$ in MATLAB or Mathematica? If so, ...
0
votes
2answers
1k views

How to plot a phase portrait for this system of differential equations?

I beg your help.. I'd like the phase portrait for this system. I don't know how to use Mathematica/Matlab ... :( If anyone can make this portrait and post a print screen here, I would thank you ...
0
votes
2answers
549 views

How to solve Ax=0.. with 4 unknowns and 4 linear equations

I am trying to solve 4 linear equations for a 3D triangulation problem to create a function in matlab code. I have 4 equations such as aX + bY + cZ + dW = 0 eX + fY + gZ + hW = 0 iX + jY + kZ + lW ...
0
votes
1answer
76 views

Plot of recurring system in MATLAB, Lozi map

I need to write this recurring system in MATLAB $$ x_{n+1}=1-a|x_n|+y_n$$ $$ y_{n+1}=bx_n $$ and take its plot for every $x_i,y_i$,with let's say a=1.4 and b=0.7. $$$$This is the Lozi map. And this ...
0
votes
1answer
60 views

Solving simultaneous equations for Weibull distribution parameter estimation

What is the best way to solve the equations below using Matlab. I have the values for i, Ni, k, T and am in need of values for rho, beta and alpha. i goes up to 12 Thank you
-2
votes
0answers
58 views

Writing systems of linear equations and matlab help appreciated [duplicate]

Does anyone know how I would go about answering the following question? A traffic engineering company has installed some trac cameras along a one lane road to find a relation between the number of ...
1
vote
2answers
237 views

Solve a system of time-independent ODE's with vector constants

I have to solve numerically this set of Ordinary Differential Equations $$ \frac{dx_1}{ds} = \frac{1}{x_1} \left[x_2 \left(a + \frac{x_2}{s}\right)-\alpha x_1 z\right]$$ $$ \frac{dx_2}{ds} = ...