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Steven Lord


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MathWorks

5 236 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
how do I take the matrix A and a vector with the indexes of the rows to be considered, and takes out a vector of the mean values?
function A(meanValue) = HW3Part3Function A(meanValue) = mean((A(1:2:end,:),2)) When you define your function, the function dec...

environ 6 heures ago | 0

Answered
convert logical values to numeric values
What do you want the double array to represent? Just 0 and 1 instead on false and true? Use Jan's approach. 0 where there isn'...

environ 7 heures ago | 0

Answered
Syntax Question, Why does this equal zero?
What happens if you compute it by hand? Start with the expression in the parentheses since they're at the top level of the opera...

environ 14 heures ago | 0

Answered
Can I assign a variable to a number in a matrix from another matrix?
There's a way to do this without creating 2*n individual variables. A = magic(7); E = eig(A); w = E(1:3); m = [3; 11; -7];...

environ 17 heures ago | 0

Answered
Not Enough Input Arguments
Your function can be called with at most two inputs, and since it uses both inputs on the line you called out it must be called ...

environ 20 heures ago | 0

Answered
Convert Text into Date Format
If you have a number: x = 196307; datetime(100*x+1, 'ConvertFrom', 'yyyymmdd') If you have text: y = string(x); datetime(y,...

1 jour ago | 1

Answered
represent a function in Matlab
Let's look at your function symbolically. xo = 400; yo = 7000; x = 260; y = 6954; a = 0.5; b =0.4; K = b*xo-a*yo; % t=...

1 jour ago | 0

| accepted

Answered
Fit operation with defined variables
See the "Create Fit Options and Fit Type Before Fitting" example on the documentation page for the fit function. It uses the 'pr...

1 jour ago | 1

| accepted

Answered
Array indices must be positive integers or logical values.
If x only has one element, x(end-1) is an attempt to access element 0 of x. Arrays in MATLAB don't have an element 0. Their firs...

1 jour ago | 0

Answered
How to define these two functions?
The name gamma already has a meaning in MATLAB, and in fact it calculates the function you're trying to evaluate with your anony...

1 jour ago | 1

Answered
How do I calculate this definite integral in matlab
When I encounter a problem integrating, one of my first thoughts is to look at the function I'm trying to integrate over the int...

2 jours ago | 1

Answered
use vector as input
So you want to compute the value of e and the time required to compute that value for each element of n? A couple of suggestions...

2 jours ago | 0

Answered
How to extend the colon operator for my own class
The colon function in MATLAB for numeric inputs does not return an iterator, it returns a vector. See the documentation page for...

2 jours ago | 0

Answered
Invalid Simulink object name: loader &&& xPC:unable to load dependent module FAST_Library_Win32.dll @ MathWorks Support Team
Since you've mentioned MathWorks Support Team in the title of this question, it seems like you're looking for help from Technica...

2 jours ago | 0

Answered
How do you create a composite function in matlab?
f = @sin; g = @cos; % define it two different ways fg = @(x) f(g(x)); h = @(x) sin(cos(x)); % Compare the two approache...

2 jours ago | 0

| accepted

Answered
Comparing elements of one vector with multiple values in a matrix of different size
If the rows in A are sorted and disjoint, this does seem like a job for histcounts. Just ignore the bins representing the spaces...

2 jours ago | 1

Answered
Passing time step from ODE solver (ode23tb) to ODE function
The evaluation of 'blah' depends on all previous steps taken. That sounds like you don't have an ordinary differential equati...

3 jours ago | 2

Answered
how matlab stores graphics objects?
The Bytes column of the output of whos does not tell the "truth, whole truth, and nothing but the truth" for certain situations....

3 jours ago | 0

| accepted

Answered
Array indices must be positive or logical values
for i = 1:N j = i+0.5 y(i+1) = y(i) + h*f(x(j), y(j)); end There's no such thing as the 1.5th element of either x or y ...

4 jours ago | 0

Answered
Standalone application: console blocks program
You may be encountering the behavior described in this Stack Overflow post.

4 jours ago | 1

Answered
How to increase axis of stem plots
Use the axis function to set the limits.

4 jours ago | 0

Answered
what kind of license do I need?
I advise you to contact the Sales department and work with them to determine the license configuration that will best meet your ...

4 jours ago | 0

Answered
Random generator with constraints
A = rand(6, 4); [~, ind] = sort(A, 2)

4 jours ago | 1

Answered
Using a string to pass input argument to a function
Use comma-separated lists (CSL). The "How to Use the Comma-Separated Lists" section on that page shows both how to use CSL to pa...

4 jours ago | 1

Answered
How to find eigenvalues and eigenvectors without using built-in functions (Ex. eig)?
Without using any built-in functions? It depends -- do you consider the commands used in MEX-files to be built-in functions? In ...

4 jours ago | 0

Answered
How can I surface plot a 1000x2 matrix?
What does the data represent? X and Y coordinates of the points? If so where's the Z data? Or do you have a long, thin sheet of...

4 jours ago | 0

Answered
Symsum returns symbolic expression instead of value
What makes you believe that this summation converges? syms m f = sinh(16*pi*m/3)./sinh(4*pi*m/3); fplot(f, [0 10]) This term...

4 jours ago | 0

| accepted

Answered
Single prompt for large set of variables
How huge is the "huge set of variables"? If your function requires the user to enter hundreds or thousands of values, I would ad...

4 jours ago | 0

Answered
showing hours elapsed not date and time data
How are you importing this data from Microsoft Excel? See if the function or technique you're using to import the data can impor...

4 jours ago | 0

Answered
computing function with a variable
%{ x0=[1;2;3;4]; d0=[1118,-124,-502,-1090]; F=(x1-10*x2)^2+5*(x3-x4)^2+(x2-2*x3)^4+10*(x1-x4)^4; %} F is not a function. As...

4 jours ago | 0

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