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Bill Tubbs


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53 total contributions since 2020

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Question


How to find the 'troughs' using peak finder in Simulink Scope
I've been using the Peak Finder Measurements tool in the Simulink scope output to find the peak of the system responses. But if...

11 days ago | 0 answers | 0

0

answers

Answered
How to check if two transfer functions are the same?
Based on comments from Paul above I offer these functions as a solution: function c = is_equal_tf(G1,G2) c = almost_zero_s...

18 days ago | 0

Question


Basic math operations on contents of a cell array
Is there any reason why basic math operations don't work with cell arrays? Seems to me it would extremely useful and efficient ...

20 days ago | 2 answers | 0

2

answers

Question


Best way to resample the output of a Simulink simulation with variable time step into a signal with a fixed sample time
I have a simulation model that runs with a variable timestep: (I don't want to change this) For the purpose of system identi...

26 days ago | 1 answer | 0

1

answer

Question


How to turn off text interpreter when plotting timeseries objects
I am plotting timeseries objects using plot. My variable names include underscores (e.g. 'ABC_DEF') and I do not want these int...

1 month ago | 2 answers | 0

2

answers

Question


Evaluate function over a mesh grid (without for loops)
Is there a way to evaluate a function that takes an [x, y] vector as input over a grid of points? Here is the function I want t...

1 month ago | 2 answers | 0

2

answers

Answered
Why do I get the warning "MATLAB:dispatcher:InexactCaseMatch Cannot find an exact (case-sensitive) match for 'startup'" on MATLAB startup?
For me the problem started after I added a path to a module that I am using for a course. The scripts in this module are launch...

2 months ago | 0

Answered
Why are symbolic expressions being rounded?
Mathworks technical support have diagnosed the problem. Don't know what caused it originally but the 'FloatingPointOutput' sett...

3 months ago | 0

| accepted

Question


Why are symbolic expressions being rounded?
I'm deriving some expressions symbolically and then substituting values and computing the results and I only recently noticed th...

3 months ago | 2 answers | 0

2

answers

Answered
Trying to set parameter values in a Simulink model using a parameter structure
I gave up on trying to figure out the ParameterStructure method and ended up doing it this way which I assume is the standard wa...

3 months ago | 0

Question


How to get subscripts in the legend of a Nichols plot?
How do I put subscripts in a Nichols plot legend? This works fine in a normal plot: figure plot([0 1],[3 4]); hold on plot([...

3 months ago | 1 answer | 0

1

answer

Question


Trying to set parameter values in a Simulink model using a parameter structure
I'm following the docmentation here in an attempt to set up a Simulink model so I can apply a set of parameter values to it befo...

3 months ago | 1 answer | 0

1

answer

Answered
I get Error: Invalid expression. Check for missing or extra characters. when commenting out lines in a multi-line statement
Here is one solution but it's hardly very convenient and contrary to commenting-out in other languages: y = ... 1 + ... ...%2...

3 months ago | 0

Question


I get Error: Invalid expression. Check for missing or extra characters. when commenting out lines in a multi-line statement
It seems you can't comment-out entire lines in MATLAB within a multi-line statement. Or am I doing it wrong. A few examples be...

3 months ago | 2 answers | 0

2

answers

Answered
How to implement an RST controller in Simulink?
After some further diagnosis, I think I have solved the problem. The default setting of the Discrete-Time Integrator block is '...

3 months ago | 0

Question


How to implement an RST controller in Simulink?
Every time I search for help on this I am taken to the following page: RST Controller But I don't have access to the Simscape ...

3 months ago | 1 answer | 0

1

answer

Answered
How to simulate a discrete linear system model with a user-specified disturbance signal?
I found the answer in the documentation: opt = simOptions('AddNoise',true,'NoiseData',e); Turns out I was looking at the wrong...

3 months ago | 0

| accepted

Question


How to simulate a discrete linear system model with a user-specified disturbance signal?
I'm using idpoly and sim to simulate a discrete linear system so I can compare the output with my own (hand-coded) simulation. ...

3 months ago | 1 answer | 0

1

answer

Answered
Raise a scalar to a descending series of powers in an array
Here is the correct answer I think. Element-wise operation: 0.8.^(3:-1:1)

3 months ago | 0

| accepted

Answered
Raise a scalar to a descending series of powers in an array
I found this solution: power(0.8,3:-1:1) ans = 0.5120 0.6400 0.8000 But still surprised if it can't be done ...

3 months ago | 0

Question


Raise a scalar to a descending series of powers in an array
I'm trying to compute a series of powers of a scalar. This seems to work but the result is not what I expected: 0.8^1:3 ans...

3 months ago | 3 answers | 0

3

answers

Answered
How to check if two transfer functions are the same?
There is an answer on Stackoverflow: However, it does not work directly in my case: isequal(tf(C1), Gc1) ans = logical...

3 months ago | 0

Question


How to check if two transfer functions are the same?
I want to verify that two transfer functions are equal. For example: Kc = 0.4262; Ti=1.35; C1 = pidstd(Kc,Ti); tf(C1) s = t...

3 months ago | 3 answers | 0

3

answers

Question


Solve equation that has a complex subexpression
I want to solve the following equation for omega: where So I tried this: syms s omega G(s) G(s) = 10/(s*(1+s)*(1+0.2*s))...

4 months ago | 1 answer | 0

1

answer

Question


How to assign values to an array with broadcasting
Is there any way to do broadcasting while assigning values to an array? I know how to broadcast a computation: G = zeros(3) G...

4 months ago | 1 answer | 0

1

answer

Answered
Undefined function 'workspacefunc' — How to change search path back after accidentally changing it
In the end I simply force-quitted MATLAB and restarted it and it works as normal again. (Remember to save your work first).

4 months ago | 0

| accepted

Question


Undefined function 'workspacefunc' — How to change search path back after accidentally changing it
I couldn't remember the function to check if a directory exists so I typed the following, and then accepted the suggested correc...

4 months ago | 2 answers | 0

2

answers

Question


How can I determine the order of a symbolic differential equation?
I'm writing a function that takes a differential equation in symbolic form as an argument and I want to determine the order of t...

4 months ago | 1 answer | 0

1

answer

Answered
Why do I receive License Manager Error -97?
This is far too complicated and there are too many potential solutions. I have this error after installing MATLAB on a second c...

4 months ago | 0

Answered
Can't see any effect of NoiseVariance with idpoly and lsim
Maybe lsim is not the right function to use. I solved the problem by using sim instead, which has options including to add nois...

5 months ago | 0

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