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Steven Lord


MathWorks

2,953 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 can I average datetimes of my array?
Convert your table to a timetable using table2timetable. Once you have your timetable call retime on it.

3 hours ago | 0

Answered
row dimension of aeq is inconsistent with length of beq. Help me pls.
You passed the inputs into fmincon in the wrong order. From the documentation page, the syntax you're calling is: x = fmincon(f...

4 hours ago | 0

| accepted

Answered
Pan does not work
Run this command: which -all pan From the error message it sounds like you've created a Simulink model named pan that is takin...

4 hours ago | 0

Answered
how tocreate a new array that select the columns with a specific prefix in the header row
Read your data into a table array using readtable. Since I don't have your spreadsheet, I'll just create a sample table using th...

1 day ago | 1

Answered
Re-hash the intrinsic Matlab plot function to accept a string as a y input?
You could turn your text data into a categorical array then plot with that categorical data as the Y input. colors = categorica...

1 day ago | 1

Answered
I got "The expression to the left of the equals sign is not a valid target for an assignment."
Just eliminate that line from your code. The way you've defined x on the next line will make it complex since i is already defin...

2 days ago | 0

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Answered
Dynamic size differential equation system
There's no need for a loop here. Work on vectors. function dvhdt = myodefun(t, vh, alpha, optV, beta) % Compute N from the vh ...

2 days ago | 0

Answered
Blackjack Program -- Random Card Deal
Deal 4 cards from the deck at once. Give the dealer the first two and the player the next two. As written, your code can give t...

3 days ago | 0

Answered
symbolic variable multiplication with numerical matrix
When you perform that multiplication, Symbolic Math Toolbox converts your numbers into rational numbers rather than leaving them...

4 days ago | 1

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Answered
Resetting individual properties to default values: 2018b
The most straighforward way is probably to define a Hidden, Constant property holding the default value. Since it's Hidden it wo...

5 days ago | 0

Answered
How mink functions is used in 2016a or is there any alternate of this function ?
As stated at the end of the documentation page for mink, this function was "Introduced in R2017b". It does not exist in release ...

6 days ago | 0

Answered
syms wrong message, definition
syms creates an Inf value as part of its operation, and you've enabled an error breakpoint that causes MATLAB to enter debug mod...

7 days ago | 0

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Answered
suptitle in 2016a
If you are using release R2018b or later, I recommend using the sgtitle function instead of suptitle. subplot(2, 2, 1); plot(1...

7 days ago | 0

Answered
How can I create this 2D waterfall plot?
That's not a waterfall plot, at least not by my understanding. To me a waterfall plot looks like the picture shown on the waterf...

7 days ago | 0

Answered
Increasing Speed of Execution
Try the ischange function.

7 days ago | 1

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Answered
How can I represent the mean in figure
You can 'center' your data using the normalize function. As for "represent the data in figure" do you mean you want to plot the...

7 days ago | 0

Answered
Access different property from set method in class
As long as the get method for the useGpu property doesn't try to set the smaps property (leading to an infinite loop) and as lon...

7 days ago | 0

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Answered
New to MATLAB, question about num2str
I recommend not using datetime as the name of your variable as it already has a meaning in MATLAB. If you want to use a datetime...

7 days ago | 1

Answered
realmax + 1 infinity?
If you handed Bill Gates or Scrooge McDuck a $1 bill, it doesn't change what he'll report for his net worth. A single dollar is ...

7 days ago | 1

Answered
Compatibility of R2015b on windows server 2016
According to the previous release system requirements page, Windows Server 2016 is not listed as a supported operating systems f...

8 days ago | 0

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Answered
How to change values of x axis from numbers to dates
Are you trying to change just the labels, or are you trying to change the underlying data in the plot? If the former, try the x...

8 days ago | 0

Answered
Trouble using retime to obtain 1 year of hourly average values from 15 years of hourly average values
So if I understand correctly, you want to take the mean of (for example) your data points for 1 AM January 1st 2018, 1 AM Januar...

8 days ago | 0

Answered
syntax for random number
Take a look at the randi or randperm functions. If you need to generate numbers from a set that contains non-integer values, or...

8 days ago | 0

Answered
having error "Attempt to execute SCRIPT plot as a function: C:\Azam\non-linear\files\plot.m" in matlab when I want to plot
Rename the file C:\Azam\non-linear\files\plot.m to something else. While it exists in the current directory or in a directory on...

9 days ago | 0

Answered
Calculating within-month standard deviation from daily return data
Since this message was originally written we've introduced the timetable data type. I'd store the data in a timetable and call r...

9 days ago | 0

Answered
Find out if number is divisible by x
Take a look at the rem and mod functions.

10 days ago | 1

Answered
What does 'Colormap' do to the image with double/float pixels?
Since your variable name is img, I assume you're planning to display this using the image function in MATLAB. If so look at the ...

10 days ago | 0

Answered
prime staircase (coding)
Search the documentation for "prime" and you will find a function that will be useful to you.

10 days ago | 0

Answered
Matching based on working days
If possible, switch to using datetime instead of serial date numbers. You can use the datetime options 'ConvertFrom', 'excel' or...

10 days ago | 0

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