Steven Lord

MathWorks

Last seen: Today | Active 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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numerical integration inf to inf
Look at your function over the region in question. e=0.01; f= @(x) 1./sqrt((1-x.^2)+(e/2)*(1-x.^4)); a=-1; b=1; fplot(f, [-...

20 hours ago | 0

Answered
Viewing Symbolic Matrix Entries in Variable Tab?
If you're planning to use the symbolic expression in a loop you may want to create a MATLAB function file from it using matlabFu...

1 day ago | 0

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Grey Wolf optimizer in matlab
The ability to define local functions in scripts was introduced in release R2016b.

2 days ago | 0

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Answered
App designer: How to define self-referring properties?
That code does not define a variable named x. It defines an object property named x. You're assuming that defining one property...

4 days ago | 1

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Answered
rng usability missing seed functionality
It looks like using "seeds" is being considered "old fashioned" in Matlab 2022b, and there is a warning about it suggesting it w...

4 days ago | 0

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Answered
How do I use matlab.uitest.TestCase to open my app once and perform multple function tests?
You could do this by opening your app in a TestClassSetup method and storing a handle to it in a property of your test class, bu...

5 days ago | 1

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Answered
How can I access the following builtin function code? [L,p] = chol(A,'lower')
We don't distribute the source code for the built-in chol function.

5 days ago | 0

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Answered
Trying to Increase efficiency by avoiding using If statements to select data
Can you dynamically create and access variables with numbered names like x1, x2, x3, etc. or similar names like L_Data and R_Dat...

5 days ago | 0

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Is Home version an annual-basis or one-time purchase?
For your first question does the MATLAB Home product page (and the FAQ at the end of that page) provide you with sufficient info...

6 days ago | 0

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How to Convert symbolic variables to numeric
If it contains no symbolic variable use double. two = sym(2); sqrt2 = sqrt(two) x = double(sqrt2) If it does contain a symbo...

6 days ago | 0

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Why in the Test Manager; option of select New > Test for C/C++ Code is not appearing?
According to the Release Notes the capability to perform C/C++ code testing in the Test Manager was introduced in release R2021a...

7 days ago | 0

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Answered
How to separate real and imaginary components from a given expression in Matlab?
syms X1 X2 XC RL Zin=((X1*XC)-1i*(X2*RL))/(RL+1i*(X1*X2*XC)); A=real(Zin) B=imag(Zin) What leads you to believe something ...

8 days ago | 1

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Answered
ODE solver not running full time span
That suggests to me that you should have received a warning but perhaps you've suppressed it? Something along the lines of "Fail...

8 days ago | 0

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What are the differences between integral and trapz?
The integral function accepts a function handle as input and computes the integral of that function over an interval by evaluati...

9 days ago | 2

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how do i solve this error: Undefined function 'imnoise' for input arguments of type 'uint8'.
The imnoise function is part of Image Processing Toolbox. Check the output of the ver function to determine if you have this too...

10 days ago | 0

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I am learning still and i have no idea how to write 8y''' - y' = cos(20t) + sin(2t) in matlab
How are you trying to solve the ODE? Numerically or symbolically? If numerically, see the van der Pol example on this documenta...

10 days ago | 0

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using linspace in a matrix incrementing by a certain number
There are several functions for creating regularly spaced vectors of given lengths depending on which three of the four paramete...

12 days ago | 0

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Can we get functions from the curve fitting toolbox?
You can evaluate a fit as shown by the sections on this documentation page and this documentation page whose names start with "E...

12 days ago | 0

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MATLAB switching between integer and floating numbers in a loop during computation
What you're missing is that 0.1 is not exactly one tenth. Welcome to the world of floating point arithmetic. See the "Avoiding C...

13 days ago | 0

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Answered
MATLAB 'copy command' has unrecognised function or variable
The command is correct. I just tried it and it opened the example as I expected. From the Release Notes for release R2022b, "Ma...

13 days ago | 0

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How can I replace inline
To convert a symbolic expression into something you can evaluate numerically use the matlabFunction function.

14 days ago | 0

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where is the assised function in the example of using cycle-GAN denoise?
In general, to access helper functions for an example you should open the example in MATLAB (either your desktop installation of...

14 days ago | 0

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Unrecognized property string for class Panel
Since handles.fitting1 is a Panel object according to the error message, let's look at the list of Panel properties and see if S...

14 days ago | 0

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Answered
How can i found the infelction point from the data and remove the data before the first and last infelction points.
The ischange, islocalmin, and/or islocalmax functions may be of use to you, as might the corresponding Live Editor Tasks Find Ch...

15 days ago | 0

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How to make a function and input another function
I think what you want is: y = bbb(@humps, 0.5, 1) function [i] = bbb (r,a,b) i=r(a)-r(b); end

15 days ago | 1

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Getting error : Unrecognized field name "array".
Does this command indicate that train.mat contains a variable named array? whos -file train.mat % or whos('-file', 'train.mat')...

15 days ago | 0

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Using strjoin to put as a variable name in a table
Specify VariableNames as either a cell array containing char vectors or as a string array. Don't specify them as a cell array co...

16 days ago | 1

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Answered
Why is 'step' function not accessible (MATLAB online and installed)
As far as I'm aware none of the functions named step in MATLAB can be called with no input arguments. Is this perhaps a script o...

16 days ago | 0

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Genvarname for array of structs with indexing
Can you dynamically create variables with numbered names like AB1, AB2, AB3, etc.? Yes. Should you do this? The general consens...

18 days ago | 0

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Answered
Time-based integration of ODEs
The problem you've written out looks quite similar to the "Pass Extra Parameters to ODE Function" example on the ode45 documenta...

18 days ago | 0

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