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Walter Roberson


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44,936 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
Problem in displaying numbers
format long g

3 hours ago | 0

Answered
Compare and select values from an matrix.
min(A(1:2:end,:), A(2:2:end, :))

5 hours ago | 0

Answered
Error in resizing GUIDE gui
Change line 2765 of guidefunc from if ~strcmpi(get(children(i),'Units'), 'normalized') to if hasfield(childre...

6 hours ago | 0

Answered
Using equationTomatrix changes the order of units in the final matrix. How do you maintain the order?
Pass in the vars option to the function to get the results to be in that order.

7 hours ago | 0

Answered
create a vector without for
a=1:10; b=1:10; c=1:3; d=1:5; [A, B, C, D] = ndgrid(uint8(a), uint8(b), uint8(c), uint8(d)) ; v = [A(:), B(:)...

7 hours ago | 1

| accepted

Answered
Issue with running a script calling "parts" function on the MATLAB Online R2019b
https://www.mathworks.com/matlabcentral/answers/481537-submitwithconfiguration-not-working-in-matlab-r2019b

8 hours ago | 0

Answered
VERY slow for loop
You do not use the variable i inside your for loop, so you are testing the entire energy variable of the table every time throug...

12 hours ago | 1

| accepted

Answered
How to assign numbers to letters of the alphabet. Ex. A/a=1 B/b=2
https://www.mathworks.com/help/matlab/ref/lower.html https://www.mathworks.com/help/matlab/ref/ismember.html https://www.math...

12 hours ago | 0

Answered
Unique Number Assignment To Each Time
Use the third output of unique(). Or use findgroups()

13 hours ago | 0

Answered
plotting ode warning with nor plot returned
You dsolve() and store the answer but then you try to fplot the unprocessed A and B. At the very least you would want to plot S....

17 hours ago | 0

Answered
expression is too large, symengine can't calculate
Create eqns = [obj.dx,obj.dS(:);obj.dSS(:)]; Now break that up into chunks. For example: At_a_time = 10; num_eqn = length(eq...

1 day ago | 0

Answered
Better way to pull out values from a struct
Times = arrayfun(@(S) S.callsTable.Time, CT, 'uniform', 0); T = horzcat(Times{:}); The assignment to T will fail if the Time...

1 day ago | 0

Answered
how to obtain volume data from X,Y,Z,c data to use slice() function?
N = 50; xvec = linspace(592447.8, 592463.9, N); yvec = linspace(507793.3, 507837.4, N); zvec = linspace(2553.6, 2559.9, N);...

1 day ago | 0

| accepted

Answered
Eliminate tables with more than 15% NaN data
filetables = load('C.mat'); numtables = numel(filetables); tablenames = fieldnames(filetables); droptable = false(1, numtab...

1 day ago | 2

Answered
Subplot, 1 large and 2 small
subplot(2, 2, [1 3]) %draw for A subplot(2, 2, 2) %draw for B subplot(2, 2, 4) %draw for C

1 day ago | 0

| accepted

Answered
Error using fprintf Unable to convert 'sym' value to 'double'.
fprintf(nru,'{ %.3f uta1 + %.2f uta2 = -%.2f\n',[UI1,SG13,SG12]); fprintf(nru,'{ %.3f uta1 + %.2f uta2 = -%.2f\n\n',[SG13,UI2,S...

1 day ago | 0

Answered
Calling a function from a script
Example of calling a function from a script: x = input('Input x '); y = xsquared(x); disp(y) function y = xsquared(x) ...

1 day ago | 0

Answered
Trying too run two functions in parallel where the functions have two outputs
funcs1 = {@linear_programming_bound, @linear_programming_bound}; arguments1 = {W,b,Xmins(:,j),Xmaxes(:,j); ...

1 day ago | 0

| accepted

Answered
Solving Symbolic Equations with Solve-Creating a GUI
temp = struct2cell(rptas); results = vertcat(temp{:}); However, you need to be careful with this, as the order of fields in rp...

1 day ago | 0

Answered
Cell2mat not working for unequal length cell data/array
Nmsg = length(canMsgs.Data); msglen = cellfun(@length, canMsgs.Data); maxlen = max(msglen); C = nan(Nmsg, maxlen); for i = 1...

1 day ago | 0

Answered
solving equation with if statements
syms theta kappa alpha time y real eqn = y == piecewise(time < alpha, exp(-kappa*time), exp(-kappa)*exp(-theta*(time-alpha))...

1 day ago | 0

Answered
How to read a binary file with below description?
filename = 'appropriatefile.les'; [fid, msg] = fopen(filename); if fid < 0 error('Filed to open file "%s" because "%s"', ...

1 day ago | 0

Answered
I want to understand a function "fastmarchingmex" .
The source code for that function is available to employees and interns of Mathworks, but not to the public.

2 days ago | 0

Answered
Concerning some error For Loop in my optimal control problem
Inside a quoted string 'i' the symbolic engine will always interpret 'i' as sqrt(-1) and never as the current value of i You ...

2 days ago | 0

Answered
how to read complex file data to matrix
Sometimes easiest is to read the file as a character vector, use regexp to remove the space around the sign of the imaginary par...

2 days ago | 0

Answered
Unable to display symbolic object because 'symengine' was reset
You install more RAM. You are running out of memory during the symbolic computation. You should probably be using sig\der ins...

2 days ago | 0

Answered
GUI to interface Matlab with Omicron (Significance of the syntex used)
It is not impossible that there is a significance to the ' at that point, but chances are not high. For there to be a signifi...

2 days ago | 0

Answered
How to set() plot in matlab with cell array
You cannot do that. When you have multiple lines to plot then each of them must have its own line object h = plot(x, y_with...

2 days ago | 0

Answered
Build error: C++ compiler produced errors. See the Build Log for further details
You must install Visual Studio to use GPU Coder.

2 days ago | 0

| accepted

Answered
Code Explaination (For Loop)
The code is doing linear interpolation between column 4 and column 5, using abs(x) as the portion of the way between the columns...

2 days ago | 0

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