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Steven Lord


MathWorks

3,369 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
fmincon with external multi-input functions
Use one of the techniques described on this documentation page. While that page specifically mentions fzero and integral, the te...

약 5시간 ago | 0

Answered
How to compute the moving average of a signal with 6-hour window length and shifted 15 min at a time?
Use movmean with a datetime or duration SamplePoints input. Specify the window using a duration array.

1일 ago | 0

Answered
Keep getting Parse error here
There are two parse errors in that code, both where you've forgotten a comma between indices 256 and the colon character. plot(...

3일 ago | 0

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2 integrals at once?
The integral function doesn't care what name your integrand function uses for its input argument. All it really cares about is t...

3일 ago | 0

Answered
How do I get my license and activation key
If you purchased MATLAB from the online store, I believe you should have received an email with instructions on how to download ...

3일 ago | 0

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How to fill a graph exclusing given points?
Let's make a random (well, not so random, more arbitrary) polygon. A = nsidedpoly(5, 'Center', [1 1], 'Radius', 2); If you wan...

3일 ago | 1

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Answered
Extreme points finding from set
I suspect some combination of islocalmin, islocalmax, and/or ischange will identify the points you've called out with + markers ...

4일 ago | 0

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fill a polygon with a hole
Consider creating and plotting a polyshape. You will receive a warning but depending on how you've generated your data you may b...

4일 ago | 0

Answered
How to unfix the seed with Matlab engine?
Every time you call matlab.engine.start_matlab you're starting a new MATLAB process. See this documentation page for how to "Gen...

4일 ago | 0

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Answered
How to generate -1, 0 and 1?
If you want to map ranges of values in your original data to the values -1, 0, and 1 you could discretize your data. Use the syn...

4일 ago | 0

Answered
How to control the randomness of algorithm
See the three topics in the "Control Random Number Generation" section on this documentation page.

4일 ago | 0

Answered
round off problem in matlab
Based on that display I suspect one or both of the variables zcdOut or slope_count are stored in an integer class. When you comb...

4일 ago | 0

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Answered
HOW to download 2019b iso disc image
As per this message if you are a licensed end user you will need to ask your license administrator to download it.

4일 ago | 0

Answered
I cannot open the following tutorial in R2018a version. Photovoltaic Thermal (PV/T) Hybrid Solar Panel
This example was introduced in Simscape Electrical in release R2019b, according to the Release Notes. It doesn't exist in earlie...

4일 ago | 0

Answered
Banded Matrix Solver in Matlab
Since you've tagged this question with "sparse", try just using the backslash operator. The flowchart on that documentation page...

5일 ago | 1

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Answered
accuracy problems in uint64 numbers
It really depends on how you performed your computations. Let's take a somewhat large number, 3^40. xDouble = 3^40; xUint64 = ...

5일 ago | 1

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Answered
PLOT THE GRAPH OF VECTOR FUNCTIONS
If you have a picture in your mind of how you want the graph to look, open the Plots tab in the Toolstrip and click the triangle...

5일 ago | 0

Answered
Convert table and obtain column values
Use ismissing to locate the missing values (you can tell ismissing what it should consider as a missing value) then use the logi...

5일 ago | 0

Answered
What is the best way to insure that all of my functions are using the same constant values?
You could define a class with Constant properties. classdef myconstants properties(Constant) g = 9.8; g_...

6일 ago | 4

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Answered
can I return more than one argument in the "odefun" when called from ode45
What you've described sounds not like an ordinary differential equation (ODE) but like a delay differential equation (DDE). This...

6일 ago | 1

Answered
Find specific date/time from a series of datenums
If you're going to be doing a lot of processing of this data based on the times, consider turning your column of date numbers in...

6일 ago | 0

Answered
Undefined function or variable 'ranova'
The only ranova function I see in the documentation is this one. In order to call this function, the first input must be a Repea...

6일 ago | 0

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Answered
Write class methods outside the class file
Rather than defining the class methods in the classdef file to call a separate function, I'd just define them in a separate file...

7일 ago | 1

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Answered
Event function with multiple events
When you define your options structure with: option2 = odeset('Events', @comp); the ODE solver will call your Events function ...

7일 ago | 0

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Answered
Extract Variable/column with variable name from table
In what form do you want the extracted variables to be stored? A = magic(4); T = array2table(A) % Variable names A1 through A4...

7일 ago | 0

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Answered
Roots function is solving eigth order polynomial equation as fifth order.
Specify the 'All' option in your call to coeffs to return all the coefficients, even those that are 0.

9일 ago | 0

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Answered
Separate out every fourth element of a Vector
If by " so you have to make it clear that this is not the intention." you mean you don't want to delete every fourth element but...

10일 ago | 0

Answered
Create variable from an excel entry
Are you required to store this data in an Excel spreadsheet? I'd prefer storing this in a plain text file. Plot.Shift=20; Plot...

10일 ago | 0

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