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Steven Lord


MathWorks

3,650 total contributions since 2002

I joined The MathWorks in the Technical Support department during the summer of 2001 and transferred into the Quality Engineering department in March of 2004. I now work qualifying the core MATLAB numerical functions (PLUS, MINUS, LU, FFT, ODE45, etc.)
Professional Interests: mathematics, MATLAB

For assistance with MATLAB question please post to MATLAB Answers or contact Technical Support using the Contact Us link in the upper-right corner of the page instead of contacting me directly.

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Answered
wlan toolbox is incompleted
There's a note at the end of the documentation page that states this function was introduced in release R2019a. If you're using ...

17 hours ago | 0

Answered
Using now() in different time zones (or with daylight saving time)
If you want control over the time zone, you probably want to use datetime instead of now. N1 = datetime('now', 'TimeZone', 'loc...

1 day ago | 0

| accepted

Answered
How to override inherited methods?
You can't do what you asked. If you could, you could relax the property setting validation to the point where your subClass inst...

2 days ago | 0

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Answered
Why is format long providing a strange result?
I recommend using format longg instead of format long for this case.

2 days ago | 1

Answered
Set properties of child objects without synchronisation errors
Let's take a step back from the code for a second. Can you describe the design of your system for which this set of classes will...

2 days ago | 0

Answered
How to require a custom class type with addRequired?
You probably want to use addParameter instead of addRequired. If you're using release R2019b or later, consider using function ...

2 days ago | 0

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Answered
Replacing <undefined> in categoricals or defining a default value
You could fillmissing to fill in the <undefined> entries, but if you want to leave them as missing data for future processing yo...

2 days ago | 0

Answered
How would I use Voronoi and/or Delaunay Triangulation methods for information on polygons
Why not just create a polyshape or an array of polyshape objects on which to operate? The NumRegions property gives you the numb...

2 days ago | 0

Answered
How to solve a ODE that is a function of a cubic polynomial f(x) = 0?
This doesn't look like a system of ODEs. The presence of the variable d in the first set of curly braces threw me for a second, ...

3 days ago | 0

Answered
Why is my for loop getting faster and faster?
This doesn't strike me as a bug. I suspect this is due to the execution engine introduced in release R2015b (which uses just-in-...

3 days ago | 0

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Answered
cannot modify plot axes as per documentation
Can you post the exact URL for the documentation page that says you can change the plot units by right-clicking, so we can see e...

3 days ago | 1

Answered
LDU factorization matrices help.
Use the ldl function.

4 days ago | 0

Answered
Find the data same week day one year ago.
You want the date exactly 52 calendar weeks ago? datetime('today')-calweeks(52)

5 days ago | 0

Answered
Derivative using datenum format vector
Use the minutes function to compute the difference between two elements of a datetime array (or two datetime arrays) in terms of...

5 days ago | 0

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Answered
ode45 for 4 DOF system - How to do with Matrices?
Is there a reason you're computing the inverse of the mass matrix and performing that multiplication instead of using odeset to ...

5 days ago | 0

Answered
simulering.m Line: 17 Column: 7 Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.
for v_(size(t))=v_(size(t)-1)+f*i*F_red-Q_ud; That's not valid MATLAB syntax. It looks like you may be trying to create variabl...

5 days ago | 0

Answered
Compare nearby elements in array
I think the islocalmax function, specifying both the dimension over which to operate and a 'ProminenceWindow', will do what you ...

5 days ago | 0

Answered
Decision Branching Error in matlab onramp
That might be checking that the densities that are printed as text when doPlot is 0 exactly match the densities that would be pr...

6 days ago | 1

| accepted

Answered
Solving Linear System of Equations with a Real Parameter
What do you know and what are you trying to find? Do you know the value of and you're trying to find the X values? If so, build...

6 days ago | 0

Answered
How to set title for matlab.graphics.primitive.Image ?
|image| objects don't have either a String or a Title property. The |axes| in which |image| objects are contained don't have a S...

6 days ago | 0

Answered
retime function not working
The variable tt is a |timetable|, but is MeanTempC? Nowhere in your code do you define it, but from the error I would guess it i...

7 days ago | 0

| accepted

Answered
Not sure why vector changes assignment when using ode45
[~,out3]=ode45(@thirdfun,t,y0,vector) This isn't the right way to pass a third input (beyond the two that |ode45| passes in...

7 days ago | 0

| accepted

Answered
How do I generate a node graph of Matrix of resistors with a given pattern.
So you just want a rectangular grid of nodes with each connected to its neighbors above, below, left, and right except for nodes...

7 days ago | 0

Answered
Splitting A String into variables
The code you posted already does this. >> a=input('enter calc: ','s') enter calc: 1+1 a = '1+1' >> a(1) ans = ...

7 days ago | 0

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Answered
Why this algorithm produces a relative error?
Walk through your code, line by line. How many times does MATLAB execute the body of your while loop? I think you want to itera...

7 days ago | 0

Answered
How to write Continue Long Statements on Multiple Lines ?
Another way to do this, with a sufficiently recent release of MATLAB, is to join elements of a string array together with the re...

7 days ago | 1

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Answered
Element-wise Conditional Statements in Script
Use the max function with two inputs.

8 days ago | 0

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Answered
Matlab Bingo Game card
randperm accepts a scalar (just one number) as its first input. You could generate a set of random numbers from 1 to 15 and use...

10 days ago | 0

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Answered
How do I get my function to form the derivative for Newton-Method
The diff function doesn't know how to operate on arbitrary function handles, including anonymous function handles. For functions...

10 days ago | 1

Answered
outputLimits function not found
Do you have Image Processing Toolbox installed? It was introduced in that toolbox in release R2013a, according to the documenta...

12 days ago | 0

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