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Steven Lord


MathWorks

3,655 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
Out of memory (infinite recursion) running a stochastic collocation
[mean, stdev] = Stochastic_Collocation(x,nomforce); You call your function inside itself, which causes your function to cal...

14 hours ago | 1

| accepted

Answered
Issue with atan2(.)
The atan2 function included in MATLAB requires exactly two input arguments. Therefore you're likely calling a different atan2.m ...

15 hours ago | 0

Answered
Pre-allocating memory for a while loop
I'm running a code that is based on a while loop to similate a chemical process. It simulates an added amount of species each se...

23 hours ago | 0

Answered
Is there any option to use boxlabelDatastore function in Matlab 2017b?
This function was introduced in Computer Vision Toolbox in release R2019b according to the note at the end of its documentation ...

23 hours ago | 0

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Answered
Wrong left and right assignment error
for n= 1:1:100 l(n) = n.*(a.*b.*c); When you execute that second line of code, n is a scalar (size 1-by-1.) The variables ...

23 hours ago | 0

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 ...

3 days 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...

4 days ago | 0

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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...

5 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.

5 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...

5 days ago | 1

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 ...

5 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...

5 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...

5 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, ...

6 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-...

6 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...

6 days ago | 1

Answered
LDU factorization matrices help.
Use the ldl function.

7 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)

8 days ago | 0

| accepted

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...

8 days ago | 0

| accepted

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 ...

8 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...

8 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 ...

8 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...

8 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...

8 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...

9 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...

10 days ago | 0

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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...

10 days ago | 0

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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...

10 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 = ...

10 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...

10 days ago | 1

| accepted

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