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Walter Roberson


42,607 total contributions since 2011

I do not do free private consulting. If you want to bring my attention to something, send a link to the MATLAB Answers location.

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Answered
How to find all coordinates of extremes of two variable function?
https://www.mathworks.com/help/matlab/ref/polyder.html and roots()

5 hours ago | 0

Answered
How to edit scatter plot legend?
Every scatter call generates a graphics object and by default legend draws labels by order of graphics object.

5 hours ago | 0

Answered
is there any way to replace this code part with an equivalent part that runs faster?
As you appear to be running those in a loop, move the ones(300,500) to outside the loop. You do not appear to be...

7 hours ago | 0

Answered
How to display multiple string outputs in a static text box in GUI
Set the 'Max' property of the uicontrol style 'text' to more than 1. The text box will then be able to display a cell array of c...

7 hours ago | 0

Answered
case of two mappings
%mapping #1: x -> x^2 %mapping #2: x -> x/2 + 1 mapping1 = @(x) x.^2; mapping2 = @(x) x/2 + 1; map1_2 = @(x) mapping2(ma...

9 hours ago | 0

Answered
Image aquisition with high speed camera
The approaches you describe cannot work. You need a hardware trigger for constant frame rate. However if you were using an ni...

14 hours ago | 0

Answered
Can I set "extents" on a ribbon plot
xlim() and ylim() and zlim()

14 hours ago | 0

Answered
Typing an equation in matlab with greek letters
syms kB T D0 Pi = evalin(symengine, '`π`'); nu = evalin(symengine, '`η`'); rs=(kB*T)/(4*Pi*nu*D0); rs = (T*kB)/(4*D0*`η`...

21 hours ago | 0

| accepted

Answered
How to pcolor and convert a matrix 4D to 2D?
slice() is the easiest way, but you can just index and squeeze() and pcolor if the depth is one of the levels exactly matching a...

1 day ago | 0

Answered
how convert pixel to mm for a mat file using Matlab?
Pixels have no inherent size. 11x11 matrix of pixels could be representing picometers or gigaparsecs. You need some kind of refe...

1 day ago | 0

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Answered
vec2ind problem?
The behavior for that case is undefined, so it is permitted to return anything it wants.

1 day ago | 0

Answered
GUI break button in a while loop
At the end of the while loop you need to add handles = guidata(gcf); so that the local copy of handles gets updated with the m...

1 day ago | 0

Answered
Solving derivative in point takes to long
The language used by the symbolic toolbox has never been compatible with execution by taking the character version of a symbolic...

1 day ago | 0

Answered
Is it not possible to run a dockerized .NET program developed in Windows, using the Matlab Runtime in a linux container?
The runtime is not cross platform. MCR is operating system specific and can only be used to run code that you could run in MATLA...

1 day ago | 0

Answered
hyper text display problem: " and ' inside href = " "
Code the inner " as " or "

1 day ago | 0

Answered
What does the following message mean?"Unable to perform assignment because the size of the left side is 50-by-150 and the size of the right side is 50-by-150-by-3."
50x150x3 means 50 rows, 150 columns, and 3 color planes. Your image july is an RGB image, even if it looks grayscale. You probab...

2 days ago | 0

| accepted

Answered
Can you help me with ode45?
[t,y] = ode45(@odefun,tspan,y0)

2 days ago | 0

Answered
How to i make the equivalent of the function scatter3 from matlab into Simulink ?
You can call scatter3() from a MATLAB Function Block in Simulink. You will probably want to use persistent to remember the axes...

2 days ago | 0

Answered
solving memory problem for this code
You cannot fix that. combnk(1:n,newn) takes all combinations of 1:n, newn at a time, where your n is 42, and newn is 41 down to ...

3 days ago | 0

Answered
Overlay curves on an existing surface plot
plot() pretty much creates lines with Z coordinate 0. surf() is going to be using 3D coordinates. Unless your surface happens to...

3 days ago | 0

Answered
How to adjust the same size of each subplot in one figure?
I confirm that subplot() allocates different OuterPosition widths for different subplots -- even just for empty graphs. However ...

3 days ago | 0

| accepted

Answered
Subscripted assignment dimension mismatch.
function all_sxint = main D=1; %L=0; Pr=1; R=0.1; Sc=1; xa=0;xb=6; Lv = [-2.5:0.025:0]; nLv = length(Lv...

3 days ago | 0

| accepted

Answered
why is my code not working?
Fm0 = linspace(0.01,0.02,100); Fm= (0.25).*(((log((2.7*10^-5)+(2.51.*((Rey.*sqrt(Fm0).^-1))))).^-1).*((log((2.7*10^-5)+(2.51.*(...

3 days ago | 0

| accepted

Answered
Why my result is 0×1 empty double column vector
function[u_g] = viscosity(Pm) % viscosity() calculates viscosity of the gas at given reservoir % temperature and pressure. M_ai...

3 days ago | 0

Answered
Usage of heaviside command valid/legal for discrete time ?
heaviside() is part of the Symbolic Toolbox. It is implemented by two different functions, one of which is used when the input i...

3 days ago | 1

| accepted

Answered
error while executing textbook MATLAB code?
In your release of MATLAB, ezplot() was not compatible with plotting symbolic expressions, and fplot() had to be used instead. ...

3 days ago | 0

| accepted

Answered
Guidance from MATLAB(Mathworks) staff?
There are no applicable tags. Everyone who answers questions here is a volunteer who answers in their own time, when and if th...

3 days ago | 1

| accepted

Answered
use of train and test data
You use round(PTrain*numImageFiles) as the upper limit for train_idx, and you use the same round(PTrain*numImageFiles) as the lo...

3 days ago | 1

| accepted

Answered
Array indices must be positive integers or logical values. How to solve?
A3 (sigma3 / Ua) is a request to either call a function named A3 passing in sigma3/Ua as a parameter, or else to index a variab...

3 days ago | 0

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