Walter Roberson
Last seen: Today
45,856 total contributions since 2011I do not do free private consulting. If you want to bring my attention to something, send a link to the MATLAB Answers location.
Walter Roberson's Badges
The contributor whose answers received the most acceptances in 2019
Awarded to Walter Roberson on 01 Jan 2020
The contributor whose answers received the most acceptances in 2018
Awarded to Walter Roberson on 18 Jan 2019
The contributor whose answers received the most acceptances in 2017
Awarded to Walter Roberson on 02 Jan 2018
Solve a problem for the first time
Awarded to Walter Roberson on 10 Jun 2017
Publish your first comment or rating
Awarded to Walter Roberson on 09 Oct 2019
Contribute at least one answer each month for 36 consecutive months
Awarded to Walter Roberson on 20 Jul 2017
The contributor whose answers received the most acceptances in 2016
Awarded to Walter Roberson on 20 Jul 2017
The contributor whose answers received the most acceptances in 2015
Awarded to Walter Roberson on 20 Jul 2017
The contributor whose answers received the most acceptances in 2011
Awarded to Walter Roberson on 20 Jul 2017
The contributor whose answers received the most acceptances in 2012
Awarded to Walter Roberson on 20 Jul 2017
The contributor whose answers received the most acceptances in 2013
Awarded to Walter Roberson on 20 Jul 2017
Accept 50 answers given by other contributors
Awarded to Walter Roberson on 20 Jul 2017
Reach 25000 reputation points
Awarded to Walter Roberson on 20 Jul 2017
Answer 50 questions that were unanswered for more than 30 days
Awarded to Walter Roberson on 20 Jul 2017
100 of your answers have been accepted
Awarded to Walter Roberson on 20 Jul 2017
How do I extract the HH:MM:SS.FFF portion of a julian day time stamp?
times = regexp(Data_Time_Stamps_Cells, '\d{1,2}:\d{2}:\d{2}\.\d{3}', 'match', 'once'); But you might as well do cellfun(@(D) D...
30 minutes ago | 0
How can I change range codes in to conditional?
for Vector = randi ([0,99],1,10000) At any one time, Vector is going to be a scalar. That makes the name misleading, but it is ...
37 minutes ago | 0
can't get ny script running. What could be the problem?
w=a*randn(350,1); so w is length 350 n = 400000; for i = 1 : n so i will go to 400000 resultant(k)=proc_1(k)+w(k); k is no...
1 hour ago | 0
Creating Matlab plot with multiple mesh models, only one with CDATA
surf(x1, y1, z1, c1); hold on surf(x2, y2, z2, c2); surf(x3, y3, z3, 'facecolor', 'g') hold off
1 hour ago | 0
Converting a mathematica if statement
f = (abs(x) <= abs(y)).*sign(y); Which can be done in vectorized form. k_x = A*f; k_y = -k_x; k_z = zeros(size(k_x)); No lo...
2 hours ago | 0
How to write cell array to excel file
If the desired output is a worksheet in which the first column has 10 rows, and the second column has 5 rows, and then the next ...
3 hours ago | 1
Error in multiplying corresponding elements in matrices
syms x y h k That is equivalent to x = sym('x'); which would create x as a 1 x 1 symbolic variable. for i = 2:(N+1); x(...
3 hours ago | 0
How to build a matrix with "sum" function in its elements?
sxb = C(b) .* cumsum(A.^(1:p)) .'; You might then want to Sub = flipud(hankel(flipud(sxb)))
3 hours ago | 0
How can I modify a command from the command window?
In the command window, press up-arrow repeatedly until it offers you the command you wish to edit. Then use the arrow keys or mo...
3 hours ago | 0
Increase brightness in part of an image
Depending on how you are constructing your "complex geometry", sometimes you can construct masks to select pixels. For example y...
4 hours ago | 0
| accepted
Accessing elements of the matrices from an array of matrices
You cannot do that. Once you construct matrix = [A B C D] then MATLAB throws away all information about how the matrix was const...
4 hours ago | 0
| accepted
How do I solve a system of ODE with time-dependent parameters ( as discrete points, not as function) in MATLAB?
When parameters change in discrete ways, then those are discontinuties in the function, and the ode*() routines cannot deal with...
4 hours ago | 0
Transfer Function with Data in Table
arrayfun(@(k,d) tf(k,[d 1]), K, D) ... as a guess about what you intend. The same thing can be done in one tf() call: tf(num2...
4 hours ago | 0
How can I begin overwriting a txt file from a specific line?
You can fopen the file with 'w+' permission. You cannot go directly to the the desired line. You can though fgetl or fgets to r...
6 hours ago | 0
| accepted
R2015a compatibility with Mac OS Catalina (10.15)
R2015a is *not* compatible with Catalina.
6 hours ago | 0
Perform AND operations with multiple matrices
M = {rand(15), rand(15), rand(15)} ; c = rand(1, 3) ; cc = num2cell(c); fold(@and, cellfun(@(V,C) V == C, M, cc, 'uniform',...
13 hours ago | 0
| accepted
Using fprintf to write to multiple files simultaneously
You are correct, any one fprintf() can only write to one place at a time. You should have a look at diary
14 hours ago | 1
OFDM Trasnmitter and Receiver (Matlab Code)
https://www.mathworks.com/matlabcentral/answers/375213-how-can-replace-randi-instead-randint#answer_298378
14 hours ago | 1
You have NaNs in your constraints! Thanks for any answers！
Your last set of constraints includes X(i)<= m*Y(i) where m=inf and Y is binvar(). binvar() have a value of either 0 or 1. W...
15 hours ago | 0
integration error in matlab
When the Symbolic Toolbox is not able to integrate a function, then it returns a placeholder int() expression showing where the ...
15 hours ago | 0
fzero of function 3 variables
fzero() is designed for single functions of one variables that return scalar values. fsolve() from the Optimization toolbox can...
15 hours ago | 0
how to prevent printing output of Neural Network in command line
P = [1 2 3]; T = [2.0 4.1 5.9]; evalc('net = newrb(P,T)');
20 hours ago | 0
| accepted
Getting a warning when I fplot
fplot passes a vector of values into the function, so in C, T will be a vector of values. But you are using T as the upper bound...
23 hours ago | 0
imshow(uint8(imagematrix)) and imshow(int8(imagematrix)) gives different results although pixel values are between 0-255
>> uint8(255) ans = uint8 255 >> int8(uint8(255)) ans = int8 127 When you int8() data that is in the range 0...
24 hours ago | 1
| accepted
Is there a way to find a global minimum using genetic algorithm?
Genetic algorithms use the function handles they are given as "black boxes" (ga cannot examine how the function works.) In all a...
1 day ago | 1
| accepted
Ode45, evolution giving NaNs after some time, with no evidence of singularities in the equations
Your first order, e1, gets to be more than 1.0, and then the sqrt(1-x^2) gets to be complex. Problems accumulate from there. Wh...
2 days ago | 1
| accepted
Automatically create variations of the same variable?
Do not use separate variables. use a cell array. You can have a table of range entries and loop through a list of check boxes, p...
3 days ago | 1
| accepted
Skipping for loop with continue does not work
See http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F
3 days ago | 1
for loops and if statements
if ys >= 100 ys is a vector. When you compare a vector to a value, the result is a logical vector of results. When you...
3 days ago | 0
Increase CPU Speed - MAC
Is there any possibility to increase the number of cores you use by default? No, there is no such possibility. MATLAB's execut...
3 days ago | 0
| accepted
Select a Web Site
Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: .
Select web siteYou can also select a web site from the following list:
Americas
- América Latina (Español)
- Canada (English)
- United States (English)
Europe
- Belgium (English)
- Denmark (English)
- Deutschland (Deutsch)
- España (Español)
- Finland (English)
- France (Français)
- Ireland (English)
- Italia (Italiano)
- Luxembourg (English)
- Netherlands (English)
- Norway (English)
- Österreich (Deutsch)
- Portugal (English)
- Sweden (English)
- Switzerland
- United Kingdom (English)