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Walter Roberson


43,353 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 convert matrix indexes to cartesian coordinates
Matrices are just arrays of values and there is no inherent Cartesian coordinates associated with them. They have rows and colum...

3 hours ago | 0

Answered
interp1 for matrix
No you should use interp2 for this. The value to look up depends on two factors, depth and time, but interp1 would only take one...

3 hours ago | 0

Answered
cannot receive udp packet
This is what you asked for. You deliberately configured udp to read across datagram boundaries until it sees a termination chara...

3 hours ago | 0

Answered
Hi, I am trying to obtain accelerometer data from a GY-521 board through solely matlab, rather than using arduino code. I am a beginner to I2C and arduino, and would appreciate some help in obtaining this data. Many thanks.
This is not typically possible. Most systems do not have i2c connectors directly available. MS Windows does support the possi...

3 hours ago | 0

Answered
Error "using symengine>@()0.0" in ODE Solver
When you call matlabFunction pass 'vars', r

4 hours ago | 0

Answered
fminsearch of the sum of an array of anonymous functions with two inputs?
z1 = @(par) (log(RO)-log(par(1)))*par(2); so z1 is defined with one argument. L_W_temp{i} = @(par) -e(z1(par(1),par(2))); ...

8 hours ago | 1

Answered
How to get the longest consecutive values in a column vector and the position at which it starts
https://www.mathworks.com/matlabcentral/fileexchange/41813-runlength

17 hours ago | 0

Answered
I want the code to randomize the rows and present each row for 10 times
Decentration = [0, 0.5; 0, 0; 0, -0.5; -0.5,0; 0.5, 0]; trial = 10; n = size(Decentration, 1); idx = repmat(1:n, 1, trial); ...

18 hours ago | 1

Answered
How can i use the ceil function rightly?
>> 2.7/0.3 - 9 ans = 1.77635683940025e-15 so ceil() is correct. As to why 2.7/0.3 is not exactly 9, see http://mat...

18 hours ago | 0

Answered
quenstion about uiload in matlab
The uiload call is going to prompt the user to select a file, and then it is going to guide the user to import variables from th...

19 hours ago | 0

Answered
Time reading in matlab
%set up opt = detectImportOptions('1932.catalog', 'FileType', 'text', 'readvariablenames', false, 'HeaderLines', 10); opt = se...

20 hours ago | 0

Answered
Help in creating function , built in equation
syms x y; eqns = damontwo(x,y); solve(eqns) %% function function yin = damontwo(x,y) yin(1) = input('Enter first equ...

1 day ago | 0

Answered
Problem with indefinite integral
https://www.mathworks.com/help/symbolic/int.html#btydjvs-2 TIPS Results returned by int do not include integration constants....

1 day ago | 0

Answered
Initial guess Error using fsolve
NZ = @(a,b) a ./ (b + (a==0 & b == 0)); myfun=@(y) exp(-s2^2./2).*exp(y*s2).*NZ(1-qfunc((t1(i)-s1-rho*y+rho*s2)./sqrt(1-rho^2))...

1 day ago | 1

| accepted

Answered
XMAX must be a floating point scalar in double integral. Kindly help.
ai=a-2*(N-1)*wd-2*(N-1)*s:2*(wd+s):a-2*(N-N)*wd-2*(N-N)*s Notice the colon operators. Your ai is going to be a vector. Like...

1 day ago | 0

| accepted

Answered
Only getting the last iteration from for loop?
ar0 = zeros(100,n); int = zeros(100,n); Okay, looks like you want to create outputs named ar0 and int for r = 1:n int = fd0....

1 day ago | 0

| accepted

Answered
using solve for solving self and mutual inductance of a pmsm
Using a different programming package, I find that the solution is Lm is anything positive Pi = pi in the below w = (50000*co...

1 day ago | 0

Answered
Solving Inequalities greater than and smaller than at the same time
In sufficiently recent versions you can code solve(-15< 10*S < 15, S) However this is not documented and not recommended. It i...

1 day ago | 0

| accepted

Answered
. Find a MATLAB built in function that is used to find the lowest common denominator of fractions.
[n1, d1] = rat(1/4); [n2, d2] = rat(1/10); com = lcm(d1, d2); Now that you have the least common multple of the denominators,...

1 day ago | 0

Answered
How to catch the error thrown when unable to connect to an arduino?
>> try; arduino("/dev/cu.Bluetooth-Incoming-Port"); catch ME; disp('nan nan nah'); end nan nan nah The particular exception is...

2 days ago | 0

| accepted

Answered
How to crop specific portion of a grayscale image?
img = imread('gray4.jpg'); im = imclearborder(255-imclearborder(255-rgb2gray(img)));imshow(im); hc = sum(im,2); mask = hc >= ...

2 days ago | 0

| accepted

Answered
MOD for optimization variable
Introduce an extra integer variable and constrain equality x-3*extra = 1

2 days ago | 0

Answered
how to make data packets from digital signals
https://www.mathworks.com/help/dsp/ref/buffer.html

2 days ago | 0

Answered
how can I compare the length of two arrays?
You can look at length() However, you need to be careful about how you define length of an array. How does the length of 1 2 ...

3 days ago | 0

Answered
How to calculate average intensity of the image given in the form of a matrix?
mean2(TheArray)

3 days ago | 1

| accepted

Answered
Recording sound while acquiring data from pressure sensor that connected with arduino
You would use record(), which will permit you to continue running. You would set up a recording duration ahead of time. However...

3 days ago | 0

Answered
generate odd and even numbers from randn function in simulink
https://www.mathworks.com/help/dsp/ref/convert1dto2d.html -- reshape the vector to two rows https://www.mathworks.com/help/dsp/...

4 days ago | 0

Answered
How would I create a script to read files line-by-line to save memory
vary_every = 10000; expected_buffers = 10000; %1000000000 / 100000 group_every = 360; variances = zeros(1, expected_buffers...

4 days ago | 0

Answered
Translating sigma notation / summation / series and integral equation from Microsoft Word into MATLAB syntax and graphing / plotting
syms n t Q = @(v) sym(v); %convert to rational Pi = sym('pi'); f1 = Q(0.111627907); f2a = int((Q(-0.3072*10^(-5))*(t ...

4 days ago | 2

Answered
Why can't 32-bit values be converted to 24-bit values?
MATLAB does not have any 24 bit data type. typecast() is only for taking a block of memory and changing the interpretation of ...

4 days ago | 1

| accepted

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