Community Profile

photo

Walter Roberson


Last seen: Today 2011 以来アクティブ

I do not do free private consulting. If you want to bring my attention to something, send a link to the MATLAB Answers location. I am currently caught up to T0099119; if you are waiting on a reply from me for an older issue, please send me a reminder.

Programming Languages:
C, MATLAB, Shell, Perl, Fortran
Spoken Languages:
English

Statistics

All
  • Most Accepted 2021
  • Roberson Cup
  • Solver
  • First Review
  • Most Accepted 2019
  • Most Accepted 2018
  • Most Accepted 2017
  • 36 Month Streak
  • Most Accepted 2016
  • Most Accepted 2015
  • Most Accepted 2011
  • Most Accepted 2012

バッジを表示

Content Feed

表示方法

回答済み
Is there any other function faster than sum(A,2) to get the sum of all rows?
Switching to columns can improve performance as it allows better use of hardware cache.

約5時間 前 | 0

回答済み
unable to use solve or fsolve for linear system
those cross() calls each return a vector, and you compare the vector to [0 0 0] giving a vector result. You then try to store th...

約7時間 前 | 0

回答済み
Can we choose step size rule in fmincon?
https://www.mathworks.com/help/optim/ug/optimizing-a-simulation-or-ordinary-differential-equation.html#btfixqo shows some contro...

1日 前 | 0

回答済み
How to copy a matrix but skipping some row and column?
M = rand(24, 24); toskip = [1, 2, 4, 6, 8, 17, 19]; %version 1 M1 = M; M1(toskip, :) = []; M1(:, toskip) = []; size(M1) ...

1日 前 | 0

回答済み
Matrix is close to singular or badly scaled. Results may be inaccurate.
You have enough duplicate t values that when you calculate "a" the rank does not reach 7; rank of a2*a does not reach 7, so your...

1日 前 | 0

| 採用済み

回答済み
How to use use an anonymous function to fit data based on the fittype and fit functions.
There is no chance of fitting that function. fit() and fittype() pass in numeric data, and diff() of numeric data is always sma...

1日 前 | 0

回答済み
Speeding up fread for random position in big file
In my experience, you can be more efficient on conversion of 12 bit data than what is done by fread() If memory serves raw = u...

1日 前 | 0

回答済み
How can I get this code to work? I am trying to fit the equation that contains step and delta function to experimental data. But I am getting the following error.
Your Energy are in the 500 range. exp(pi*energy) overflows double precision. Your code then divides by large values, but you hav...

1日 前 | 0

回答済み
Is it possible to decide which line is variable names in readtable?
Yes, you can do that. For example, variable_row = 3; datatable = readtable(filename, 'VariableNamesRange', variable_row); In ...

2日 前 | 0

| 採用済み

回答済み
Double condition to find index
freq = 2000; %hz threshold = 20; %newtons significant_time = 50; %milliseconds significant_samples = ceil(significant_tim...

2日 前 | 1

| 採用済み

回答済み
How to run a .exe file in other computers without Matlab?
https://www.mathworks.com/products/compiler/matlab-runtime.html has links to download mcr 8.5 (R2015a) In https://www.mathworks...

2日 前 | 0

回答済み
Solve IVP with Taylor method of order
https://www.mathworks.com/matlabcentral/answers/1746100-whole-derivation-of-two-variable-differential-function#comment_2229660 a...

3日 前 | 0

| 採用済み

回答済み
Error in the for loop of my function
The second parameter to symsum must be a scalar symbolic variable that will be summed over. However in your code, the second par...

3日 前 | 0

回答済み
How do you create a scatter plot using select columns from app.UITable.Data?
scatter(TableName{:,2}, TableName{:,4})

3日 前 | 0

回答済み
Is it possible to get the path of a file using uigetfile() ?
[filename, filepath] = uigetfile(); if ~ischar(filename); return; end %user cancel fullname = fullfile(filepath, filename); ...

3日 前 | 1

| 採用済み

回答済み
eeg data to move a motor
Create a numeric array in which each row is a different (fixed-length) eeg sample, and in which you have another variable which ...

3日 前 | 0

| 採用済み

回答済み
Extracting Categories from array
As the Tips says, C includes all categories in A, even if A does not contain any data from a category. To see the unique values...

3日 前 | 0

回答済み
How can I determine the cluster of pixels in an image that are red or green and quantify how many of the clusters are green or red?
filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1036195/image.jpeg'; YourRGBImage = imread(filename)...

4日 前 | 0

| 採用済み

回答済み
Why there is an error in line 132? ( [Fit(1,j), tetaDE]=selectmodel2(Pop(:,j),NP,D,mphi,start,nodata,y,u);)
The following fails because you did not provide initbp() ui = [ -3.7287749e-001 1.5462074e-001 3.6396491e-001 -2.254015...

4日 前 | 0

| 採用済み

回答済み
pair-was operation on 3D image(3D matrix)
You need to give up on the algorithm. If you were able to represent the results with one byte each, you would need 3435973836800...

4日 前 | 0

回答済み
pair-was operation on 3D image(3D matrix)
findgroups() on the image. You probably are using uint8 so at most 256 different groups. Record the second output of findgroups(...

4日 前 | 0

回答済み
Order of operation using ./
The order of operations is always left to right at the same precedence except for obscure behaviour for (^-), (.^-), (^+), (.^+)...

4日 前 | 0

回答済み
I want to know how to create dynamic string array
for K = 1 : 5 out(randi(10)) = "entry #" + K; end out

4日 前 | 0

回答済み
remove all strings from nested cell array
C = num2cell(randi(9,4,10)); C(randperm(numel(C), 4)) = {"string"}; C(randperm(numel(C), 4)) = {'chars'}; C for K = 1 : ...

4日 前 | 0

回答済み
Whole derivation of two variable differential function
The equations are being careless about which variables depend on which variables, and on which variable the differentiation is w...

4日 前 | 0

回答済み
Plotting points inside a circle
maxr = 5; %create data N = 20; r = rand(1,N) * maxr; theta = rand(1,N) * 2*pi; [x, y] = pol2cart(theta, r); %plot ...

4日 前 | 0

回答済み
Current Directory for Generated Code
MATLAB Coder is designed to target embedded systems, so functionality that is not part of the C Standard Library is often not av...

4日 前 | 0

| 採用済み

回答済み
Variable Number of Arguments
The special keyword is varargin not varagin

4日 前 | 0

回答済み
Import part of dataset in a HDF5 file, by 'member' and/or 'logical array'
<https://fossies.org/linux/hdf5/examples/h5_compound.c> The approach seems to be to use the H5T utilities to create a prototy...

4日 前 | 0

回答済み
Missing Library in Simscape
https://www.mathworks.com/help/physmod/sps/ref/thermistor.html You are looking in Simscape Electronics, but you should instead...

4日 前 | 0

もっと読み込む