Steven Lord
Last seen: Today
MathWorks
5,200 total contributions since 2002I 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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15-year anniversary Scavenger Hunt finisher badge
Awarded to Steven Lord on 09 Nov 2016
Solve a problem for the first time
Awarded to Steven Lord on 23 Jan 2013
Error using sym/subindex (Bessel function)
syms k t = 0:1:100; rho = 1000; mu = 0.001; dp = 1; R = 0.05; l = 1; ram = besselzero(0,11); Since you haven't showed us...
1 hour ago | 0
Error using plot Data must be numeric, datetime, duration or an array convertible to double
Let's look at what you're trying to plot. x=[1680 1190 841 595 420 297 210 149 105 74.4 52.5 37.2 26.3 18.6 13.1 9.29 6.57 4.6...
2 hours ago | 0
How to use indexed function output as a function of original inputs?
Dot notation is indeed not defined for function handles. You can't do: f = @sin; % Commenting this code that would error so th...
2 hours ago | 0
How can I join unequal vectors by adding NaN values?
The NaN function (along with inf, zeros, and ones) behaves in a way that will help you. Negative sizes are treated as 0. a = Na...
2 hours ago | 0
How can I solve the issue showing the error " Wrong use of the `max` data type is invalid". "The first argument must be a numeric or logical value" in matlab
The max function is not defined for cell array inputs. If it were, what would you expect the result of max to be if called on th...
2 hours ago | 1
| accepted
Help with simple bisection method function while loop
Let's say your function was: f = @(x) -x.^2; and your tolerance was 1e-6. Is the tolerance satisfied if I evaluate f at x = 1?...
17 hours ago | 0
Matlab Bisection Algorithm code
This bisect(sin(x),pi/2,1.5*pi,10^-6,100) attempts to call the sin function with the contents of the variable x as input and u...
19 hours ago | 1
error: Array indices must be positive integers or logical values.
m=(1/((kw(di)^2 ... There's no such thing as element 0.05 of an array in MATLAB. Perhaps you're missing a multiplication sign t...
21 hours ago | 0
Unwanted negative solution with ode solver
Either: specify the NonNegative option using odeset to control which components of the solution are not allowed to become negat...
23 hours ago | 0
Multi Dimension Matrix Elements multiplication
If you're using release R2020b or later, see the pagemtimes function.
1 day ago | 0
ode45: use span of length 2
If you want to only evaluate the solution of your ODE at a specific set of times even if that set of times has only two elements...
1 day ago | 0
Error: File: centraldiff.m Line: 1 Column: 11 Unbalanced or unexpected parenthesis or bracket
When you define your function, the function declaration line should include the names of the variables into which the input argu...
1 day ago | 0
| accepted
Making animatedlines that dynamically change linestyle depending on conditions
h = animatedline('LineStyle', '-'); axis([0 360 -1 1]) for x = 0:360 if mod(x, 30) == 0 addpoints(h, NaN, NaN); ...
1 day ago | 0
| accepted
Versions at End-of-Life
See the Road Map on the system requirements page. If there is a specific release and operating system combination not on that l...
2 days ago | 0
Multiply Even Variables in an Array
Hint: use logical indexing twice in the onle line of code that performs this replacement.
2 days ago | 0
Time difference in 'HH:mm:ss,SSSSSS' format
t0 = '15:30:25,123456' t1 = '16:45:30,123457' theFormat = 'hh:mm:ss.SSSSSS'; timeStart = duration(replace(t0, ',', '.'), 'I...
2 days ago | 1
| accepted
error in using the function fsolve to find steady state
Don't try using a numeric solver like fsolve on a function that returns symbolic answers. Use the solve function from Symbolic M...
2 days ago | 0
What are symbolic variables in MATLAB? How they are different from normally used variables?
Symbolic variables are instances of a class provided as part of Symbolic Math Toolbox. That documentation for MATLAB does not li...
2 days ago | 1
Password issues with downladed software
Have you contacted Springer directly to ask them for the password?
2 days ago | 0
Undefined function 'ln' for input arguments of type 'double'.
The natural logarithm function in MATLAB is named log not ln. There are also log10 and log2 functions listed in the See Also sec...
3 days ago | 1
| accepted
Computation on arrays using loops
Since you seem to be describing change point detection, see the ischange function and/or the Find Change Points task in the Live...
3 days ago | 1
Check if Lat, Lon coordinate fall inside a polyshape Polygon
I would vectorize the calculations. Let's make a simple polyshape: P = polyshape([0.75 0.3 -0.4 -0.1 -0.6 -0.3 0.5], [0.1 0.6 0...
3 days ago | 0
how to change order of legends?
You can specify the handles in a particular order when you create the legend. % Sample data x = 0:360; y1 = sind(x); y2 = c...
3 days ago | 0
How to highlight isolated nodes in a graph?
You want to highlight those nodes that are not connected to any other? G = graph(sprand(10, 10, 0.05), 'upper'); h = plot(G); ...
3 days ago | 1
| accepted
Assign placement choices to student identifying their top three
See the matchpairs function.
3 days ago | 0
how to normalize a matrix?????
Use the normalize function with a dim input and the 'range' normalization method.
3 days ago | 0
Implementation of the feedforwardnet Neural Network
How are you handling the preprocessing functions and postprocessing functions? net = feedforwardnet([2]); net.inputs{1}.proces...
4 days ago | 0
| accepted
display biograph in GUI axes
If you want to display a graph in an app or GUI axes, consider building a graph or digraph object and calling plot on it. I beli...
4 days ago | 0
Group data in bins
If you just need to know in which bin each element falls, use discretize. E = 0:11; x = 10*rand(20, 1); bin = discretize(x, E...
4 days ago | 0
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