Réponse apportée
ODE45 returns NaN
t = 0 causes a problem. Try tspan = [0.1 100]; for example.

presque 4 ans il y a | 0

Réponse apportée
How can I do an elliptic curve in Matlab?
Here's one simple way: % y^2 - y = x^3 - x % y = (1 +/- sqrt(4x^3 - 4x + 1))/2 n = 1000; x = -2:1/n:2; d = sqrt(4*x.^3-...

presque 4 ans il y a | 1

Réponse apportée
Phase Portrait of ODE system
Do you mean something like this: % Part IIa. Base Case % Phase Portrait % % r=2.5; p=2; c=0.1; b=0.1; % % [x,v]=meshgr...

presque 4 ans il y a | 0

Réponse apportée
Plot with while loop
By the time you get to the plot command you only have a single value of t1 and a single value of y1 as you overwrite each of the...

presque 4 ans il y a | 0

| A accepté

Réponse apportée
How should I approach solving differential equation as function of two variables r, k?
You need to call the ode with something like [t, y] = ode45(@(t,y) deq(t,y,r,k),tVec,y0,r,k); where you pass values of r and k...

presque 4 ans il y a | 1

Réponse apportée
I need help plotting
More like this perhaps: Z1=500; Z2=50; Z3=500; u=1; tau1=(2*Z2)/(Z1+Z2); tau2=(2*Z1)/(Z1+Z2); tau3=(2*Z3)/(Z3+Z2); p1=(Z...

presque 4 ans il y a | 1

Réponse apportée
1D Heat Equation Explicit Scheme
Look at for i=1:(N) if (alpha*DELTA_t)/(DELTA_x^2)<=0.5 T(i,j+1)=T(i,j)+((alpha*DELTA_t)/((DELTA_x)^2))*(...

presque 4 ans il y a | 1

| A accepté

Réponse apportée
Solving a system of Second Order Equations
Not sure there is a symbolic solution, but it's easy enough to get a numerical one: tspan = [0 1]; % Start and end times % In...

presque 4 ans il y a | 1

Réponse apportée
How to solve 4th order Runge-Kutta for different initial conditions?
Here's a rather crude method (together with some corrections). You should be able to turn this into a much more elegant version...

presque 4 ans il y a | 1

| A accepté

Réponse apportée
1D Heat Equation Explicit Scheme (fixed)
With for i=0:0.1:50 you are trying to index variables with zero. However, Matlab's indexing starts at 1.

presque 4 ans il y a | 1

Réponse apportée
How to plot Homogeneous solution and Particular integral seperately of a second order differntial equation using ode45
ode45 just solves first order equations, so turn your second order equation into two first order ones, like so: y' = v v' = -4...

presque 4 ans il y a | 0

Réponse apportée
Trying to plot R_K 4th order, but keep getting straight line?
Check these equations F_sir = @(s,i,r) -a*s*i; % change the function as you desire G_sir = @(...

presque 4 ans il y a | 1

| A accepté

Réponse apportée
Not enough input arguments; fzero function
Replace T_mix = fzero(fun,T_mix_0); by T_mix = fzero(@fun,T_mix_0);

presque 4 ans il y a | 1

Réponse apportée
I am trying to use the trapezoidal rule to compute the flow rate of fluid through a pipe.
I think it needs to be more like this: % Velocity distribution function of the pipe % Area = pi*r^2 % dA = 2*pi*r dr % Q = V...

presque 4 ans il y a | 0

| A accepté

Réponse apportée
How to get area under the fit attained by Curve Fitting tool?
Try help trapz

presque 4 ans il y a | 0

Réponse apportée
Progressively slower performance and task constraints using matrix and loops
With these particular functions it's easy to precalculate the Jacobian function and do everything numerically (and quickly). Fo...

presque 4 ans il y a | 0

Réponse apportée
Local Stiffness Matrix Negative
How about replacing if i==2 & j==2 k=A(e)*E/(L/5); elseif i==2 & j==1 k=...

presque 4 ans il y a | 0

Réponse apportée
Save array values in a for loop
Try replacing error = max(abs(double(y1-z1(vx)))) with error(i) = max(abs(double(y1-z1(vx))));

presque 4 ans il y a | 0

| A accepté

Réponse apportée
Solving a PDE with two variables using cank nicolson method
Matlab indices start at 1, so the loops i, j and K in the following for i=0:N for j=0:M for K=0:1 f(x,y...

presque 4 ans il y a | 0

Réponse apportée
Solving a System of 2nd Order Nonlinear ODEs
You haven't passed y and z to the funcion in function dydt=mbd(M,m,g,lc,k) Probably needs to be more like function dydt=mbd(t...

presque 4 ans il y a | 0

Réponse apportée
Can I comment only a section or part of a line?
Like this: x = linspace(0,2*pi,100); y1 = sin(x); y2 = cos(x); plot(x,y1,... % comment x,y2)

presque 4 ans il y a | 0

Réponse apportée
Adding subtitle to the plot
In Matlab 2018 try title({'Main title text';'subtitle text'}) (Note the curly brackets)

presque 4 ans il y a | 0

| A accepté

Réponse apportée
Left-rotating a vector
You define B as a null vector so it doesn't have an "end". Try, simply A = [1,2,3,4,5]; B = [A(2:end) A(1)]

presque 4 ans il y a | 0

| A accepté

Réponse apportée
How can I solve this error : Invalid text character. Check for unsupported symbol, invisible character, or pasting of non-ASCII characters.
This works for me: n=input('donner le nombre de points: '); k=0; for i=1:n u1=rand;u2=rand; x=2*u1; y=2*u2...

presque 4 ans il y a | 0

Réponse apportée
Lax-Wendroff method for advection equation with periodic boundary condition
If you make dt=0.1*h/a; instead of dt=0.95*h/a; your max error reduces to 0.0355.

presque 4 ans il y a | 0

Réponse apportée
I want to solve the unknown variable t1
Well, this gets it working, though who knows if it makes any sense!" A0 =500; D0=100; c1=5; c2=10; c3=10; c4=8; a=30; a2...

presque 4 ans il y a | 0

Réponse apportée
How to make convergence plot (error VS time step) in a log-log scale among four numerical methods and exact solution?
This should give you the right idea: %% 1st-order Adams-Bashforh Solution fun = @(t,y) (y); %Function f(t,y) y0 = 1; %Initial...

presque 4 ans il y a | 0

Réponse apportée
i need some help with finding the damping ratio
Use fzero: x = [12.73, 25.36, 37.99]; y = [0.77, 0.29, 0.11]/2; zeta = fzero(@(zeta) fn(zeta,y),0.5); disp(['zeta = ' nu...

presque 4 ans il y a | 0

Réponse apportée
How to make graph that plot between Analytical Solution (Exact Solution) and Numerical Method Solution?
After Y = exactY(t2) you probably need something like: plot(t2,Y2,t2,Y) legend('AM','Exact') However, you haven't supplied th...

presque 4 ans il y a | 0

| A accepté

Réponse apportée
How to numerically solve and plot definite integral with variable upper limit
Like so: K= @(t) (sin(t)-t.*cos(t)).*sin(t); P = 0:0.1:3.1416; for i = 1:numel(P) V(i) = integral(K,0,P(i)); ...

presque 4 ans il y a | 0

| A accepté

Charger plus