# Randy Chen

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**Content Feed**

Question

how to find all possible stationary points of a system of nonlinear equations

I stumbled across this seemingly simple problem: I tried using fsolve, but I can only pass in a single initial guess. Is ther...

14 days ago | 1 answer | 0

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answerQuestion

Question about using the nonlinear model predictive control toolbox

I wonder what type of solvers is used in the nlmpcmove function? I can't seem to find relevant documentations online.

1 month ago | 0 answers | 0

### 0

answersQuestion

Array indices must be positive integers or logical values.

I have a few function scripts and a main script. The function scripts can run perfectly without errors when I manually input s...

9 months ago | 0 answers | 0

### 0

answersQuestion

the `margin` command gives incorrect gain when comparing to the actual Bode plot

I have a continuous-time tranfser function with delay , and I printed the gain and phase margin as following: [Gm0,Pm0] = mar...

12 months ago | 0 answers | 0

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answersQuestion

How to fix symbolic errors

I have the following function defined that will be used in a main script: function ke = Ke2Diso(E, nu, Xe, Ye) E_matrix = E/...

1 year ago | 1 answer | 0

### 1

answerQuestion

Need help on Control System Tuner in Simulink

I tried to use control system tuner to tune my PID controllers, but when I was setting step tracking goal, my step input signals...

1 year ago | 1 answer | 0

### 1

answerQuestion

need some help on the Linearization tool in MATLAB

According to the documentation for linearize, a linear approximation of a nonlinear plant is returned at the specific operating ...

1 year ago | 0 answers | 0

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answersQuestion

how to extract a transfer function or state space model from a Simulink model

I have built a Simulink model for an inverted pendulum and is attached here. I would like to check the settling time using the s...

1 year ago | 1 answer | 0

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answerQuestion

need some help on linearizing the plant model for an inverted pendulum in Simulink

I constructed a Simulink model for an inverted pendulum system according to this tutorial:https://ctms.engin.umich.edu/CTMS/inde...

1 year ago | 0 answers | 0

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answersQuestion

curve fit a custom polynomial

I have the following 2nd order polynomial in the r-z coordinates: Right now I have four sets of coordinats (r,z), how shoul...

1 year ago | 2 answers | 0

### 2

answersQuestion

How to fix the sym/solve error

I get the following error from my code: z = [-6.41 -12.4 2.143 102]; r = [13.58 15.7636 12.96 46.6]; syms A B C D; eq1 = A*r...

1 year ago | 1 answer | 0

### 1

answerQuestion

need some help to troubleshoot a "solution not finite" error in Simulink

I'm getting the following error on my Simulink model: I tried changing the initial conditions and reducing the fixed step...

1 year ago | 0 answers | 0

### 0

answersQuestion

Simulink simulation error: solution not finite

I encountered the following simulation error: I tried reducing the step size in the solver but it doesn't work. How should ...

1 year ago | 1 answer | 0

### 1

answerQuestion

need help on trouble shooting my Simulink controller model

I have created a simulink model for an inverted airfoil mounted on a moving cart (very similar to the inverted cart-pendulum). I...

1 year ago | 0 answers | 0

### 0

answersQuestion

need some help on modifying my simulink model

I have created a simulink model for an inverted airfoil mounted on a moving cart( similar to the classical cart-inverted pendulu...

1 year ago | 0 answers | 0

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answersQuestion

Simulink algebraic loop warning?

Can someone please explain what this warning means?

1 year ago | 1 answer | 0

### 1

answerQuestion

simulink modelling vs the actual differential equation

I didn't realize that to model a set of governing differential equations of a dynamical system in Simulink will require some mod...

1 year ago | 1 answer | 0

### 1

answerQuestion

Simulation error in Simulink

I'm getting these errors for my model in Simulink: I tried to switch to TrustRegion-based algorithm, but it failed after I ...

1 year ago | 0 answers | 0

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answersQuestion

how to solve this MATLAB solve error?

I'm trying to solve a simple set of linear equations: syms m U2 eqn1 = 0.0004*200*10^6*(-3/4*U2-sqrt(3)/4*0.05)==0; eqn2 = ...

1 year ago | 1 answer | 0

### 1

answerQuestion

define parameter values for simscape model

I'm playing around with the inverted pendulum simscape file that comes with MATLAB, but I notice some issues: All the param...

1 year ago | 1 answer | 0

### 1

answerQuestion

Old-version simscape model cannot run on MATLAB 2020

I downloaded a 2017-version simscape model and attempted to run it on MATLAB 2020, but it keeps giving me this error: I t...

1 year ago | 1 answer | 0

### 1

answerQuestion

How is the transfer function determined for a PID controller

I'm reading a tutorial on PID controller, and the transfer function for a mass-spring damper system is given as follows: wh...

1 year ago | 1 answer | 0

### 1

answerQuestion

converting symbolic function to numerical representation for integration purpose

Below are my codes attempting to compute numerical integrals using Lagrange polynomials clear all nvect=[5,15,30,50]; fcn=@(x...

1 year ago | 1 answer | 0

### 1

answerQuestion

how to solve an equation iteratively?

I need to solve the following equation and get a real number: Below are my codes. When doing this, the solution returned are a...

2 years ago | 1 answer | 0

### 1

answerQuestion

how to plot a function symbolically?

I would like to plot the following function: where g is the only known constant = 9.8. How should I plot this function z(r)...

2 years ago | 3 answers | 0

### 3

answersQuestion

plotting two legends on the same plot

I have trouble plotting two legends for two lines on the same plot . Here are my codes: p = linspace(0,1,50); v = -290*9.8*log...

2 years ago | 1 answer | 0

### 1

answerQuestion

how to select a row of data from a csv file that is imported into Matlab?

I need to read in a csv file and utilize a function that is built into matlab: [a,ecc,incl,RAAN,argp,nu,truelon,arglat,lonper] ...

2 years ago | 1 answer | 0

### 1

answerQuestion

i got some issues trying to integrate a function symbolically

I'm trying to symbolically integrate this function, but it's not working: >> syms x y s >> fun = y/((x-s)^2+y^2); >> int(fun,...

2 years ago | 1 answer | 0

### 1

answerQuestion

integrating function from -inf to +inf

I'm trying to integrate the following function from -inf to +inf with repsect to x. fun = @(x) -3.*v.^2 -4.*v.*a./((x.^2+a.^2)...

2 years ago | 1 answer | 0

### 1

answerQuestion

contour plot of stream function for a tornado

I have a stream function for a tornado and I watned to plot it using contour function, but it's not working: m1=-3000; m2 = 58...

2 years ago | 1 answer | 0