# Questions tagged [matlab]

Questions about the numerical programming language MATLAB.

157 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
0answers
338 views

### How to solve a nonlinear diffusion equation?

Consider a thin film with a perpendicular applied magnetic field $H_a$ in $z$-axis. The nonlocal relation between $H_a$, the self-field $H_\text{self}$ (generated by the eddy current $J$) and the ...
0answers
2k views

### How to solve an ode with stochastic time-dependent input

I am trying to repeat an example I found in a paper. I have to solve this ODE: $25 \ddot{x} + 15 \dot{x} + 330000 x = p(t)$ where $p(t)$ is a white noise sequence band-limited into the 10-25 Hz ...
0answers
351 views

### Optimizing rank computation for very large sparse matrices

I have a sparse matrix such as ...
0answers
2k views

### Piecewise linear approximation of an experimental data curve. Knots position constrained

I need to fit a curve, obtained from experimental data, with a piecewise linear model (4 knots and therefore 3 lines). I tried using the MATLAB function ...
0answers
993 views

### algorithm Matlab function 'stream2' and 'stream3' use to compute streamline

Can anyone explain how the MATLAB functions: stream2(x,y,z,u,v,startx,starty) and stream3(x,y,z,u,v,startx,starty) compute stream lines from vector data u and v? In the stream2.m file, it calls the ...
0answers
2k views

### The solution found by the optimization function when exitflag is negative

I'm using Matlab's fmincon to solve a constrained nonlinear optimization for varying sets of parameters in the objective function. I have 2 parameters and have 400 unique combination of these 2 ...
0answers
262 views

### Generating start point in a systematic manner for fmincon

I'm trying to generate start points for my optimization problem in Matlab. At this point Im not worried about feasibility but only a fast way to generate the points from which I could test the ...
0answers
232 views

### Generating Hessian of the Lagrangian with dynamic number of nonlinear constraints in Fmincon

I'm using interior point algorithm for solving a nonlinear optimization problem and want to provide Hessian of the Lagrangian as part of fmincon to speed up the process (running couple of thousand ...
0answers
761 views

### Fast way to compute barycentric lagrange interpolation

Is there any fast way to compute the barycentric Lagrange interpolation using matlab? something more faster than using repmat instead of for loops
0answers
171 views

...
0answers
2k views

### Simulink PDE (MATLAB)

I need to build a system in Simulink that solves a PDE, but I can't find any literature or books where it is described how to do it (especially any stuff according to modeling PDE in Simulink). ...
0answers
223 views

### Sign or cardinality constraint when solving for sparse signal

I'm currently learning about using linear and semidefinite programming to find sparse solutions to problems. In particular, finding sparse solutions where the sampling functions are sinusoidal (...
0answers
364 views

### features recognition & reconstruction of 3d mesh delaunay matlab

I managed to display the coordinates of x,y and z into a 3D mesh by using delaunay function. The coordinates are in .obj format actually and i have read it into matrix form. Now, i would like to ...
0answers
39 views

### Path constraints for state variables - fmincon, ODE45

My problem lies in constraining state variables (look for 23,24,25). I am currently using ODE45 to solve equations and fmincon to find best control variable.How would you go about solving this? Here ...
0answers
51 views

0answers
196 views

### Givens method for sparse matrix

I have a (very) large sparse matrix in CSC form and I'm supposed to factorize it. I've read that between Givens and Householder transformations, Givens is better for a sparse matrix. The problem is ...
1answer
2k views

### Faster code for double integration using Gauss-Legendre quadrature

I came with a the following code to evaluate a double integral using Gauss Legendre quadrature in MatLab ...